Research Article An Optimal Control Strategy for DC Bus ...downloads.hindawi.com/journals/tswj/2014/271087.pdf · An Optimal Control Strategy for DC Bus Voltage Regulation in Photovoltaic

Research ArticleAn Optimal Control Strategy for DC Bus Voltage Regulation inPhotovoltaic System with Battery Energy Storage

Muhamad Zalani Daud12 Azah Mohamed2 and M A Hannan2

1 School of Ocean Engineering Universiti Malaysia Terengganu 21030 Kuala Terengganu Malaysia2 Department of Electrical Electronic amp Systems Engineering Universiti Kebangsaan Malaysia 43600 Bangi Selangor Malaysia

Correspondence should be addressed to Muhamad Zalani Daud zalaniumtedumy

Received 17 February 2014 Accepted 17 March 2014 Published 24 April 2014

Academic Editors V N Dieu P Vasant and G-W Weber

Copyright copy 2014 Muhamad Zalani Daud et alThis is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

This paper presents an evaluation of an optimal DC bus voltage regulation strategy for grid-connected photovoltaic (PV) systemwith battery energy storage (BES) The BES is connected to the PV system DC bus using a DCDC buck-boost converter Theconverter facilitates the BES power chargedischarge to compensate for the DC bus voltage deviation during severe disturbanceconditions In this way the regulation of DC bus voltage of the PVBES system can be enhanced as compared to the conventionalregulation that is solely based on the voltage-sourced converter (VSC) For the grid sideVSC (G-VSC) two controlmethods namelythe voltage-mode and current-mode controls are applied For control parameter optimization the simplex optimization techniqueis applied for the G-VSC voltage- and current-mode controls including the BES DCDC buck-boost converter controllers A newset of optimized parameters are obtained for each of the power converters for comparison purposes The PSCADEMTDC-basedsimulation case studies are presented to evaluate the performance of the proposed optimized control scheme in comparison to theconventional methods

1 Introduction

Despite the many advantages offered by photovoltaic- (PV-)based renewable energy (RE) generation it suffers fromunpredictable environmental conditions and abrupt changesin system loads In addition when the PV-based RE gener-ation is grid connected the possibility of utility grid faultat the point of common connection (PCC) might result ina system breakdown or the interruption of power suppliedto critical loads One of the typical challenges in integratingsuch a variable generation to utility grid is in controlling theDC bus voltage stability within the power conversion system[1 2] The disturbances such as varying environmentalconditions system loads and fault occurrences cause theDCbus voltage to fluctuate overshoot or undershoot and sag ordip [3] Poor regulation of the DC bus voltage may result insystem instability and inferior efficiency of PV systems Theproblems above can be attributed to the poor dynamics of PVcontrol systems in comparison to the transient time from thedisturbances [4]

The instability of DC bus voltage may propagate over thePV system network where in some cases the requirementfor fast dynamic compensation devices such as diesel genera-tors or the battery energy storage (BES) for power fluctuationmanagement and fault ride by mitigation is indispensableLead-acid-type battery is currently themost preferred storagemethod for most RE based integration issues because theirmature technology provides a reasonable trade-off betweencost and performance [5 6] The importance of DC busvoltage regulation based on BES is that it provides a constantDC bus voltage seen by the grid side voltage-sourced con-verter (G-VSC) resulting in efficient power conversion whileprotecting theDCbus capacitor and theG-VSC valves againstovervoltage stress

Technically the variation in DC bus voltage can bemitigated by adjusting the duty cycle of the power con-verters responsible for voltage regulation which is normallyperformed by the proportional integral (PI) compensator[7ndash10] The PI controller is commonly characterized byits distinct parameters namely the proportional gain 119896119901

Hindawi Publishing Corporatione Scientific World JournalVolume 2014 Article ID 271087 16 pageshttpdxdoiorg1011552014271087

2 The Scientific World Journal

and the integral gain 119896119894 respectively From the literatureseveral conventional tuning strategies that have been in useinclude the hand tuning or trial and error Smith Ziegler-Nichols and pole placement methods [7] However thesetuning strategies require the determination of system transferfunction which makes the method more complex [8] Anumber of optimization methods have been developed forfine-tuning converter control parameters [9 10] but onlyfew applications used the simplex algorithm From previ-ous studies applications of the simplex algorithm are incontrolling FACTS devices [11 12] and vehicular controlsystems that employ bidirectional converters [13 14] Thispaper addresses the issue of improving DC bus voltageregulation by using G-VSC and BES with a bidirectionalDCDC buck-boost converter for the efficient performanceof grid-connected PV systems The BES connected to theDC bus of the PV system can enhance the systemrsquos dynamicperformance by controlling the chargingdischarging of BESwith a bidirectional converter when the system is subjectedto varying disturbances The optimal controls of the G-VSCand the bidirectionalDCDCconverter are investigated in theproposed control methodologies First the control methodsof the G-VSC namely the voltage-mode and current-modecontrols are assessed Second the control parameters of theG-VSC and the bidirectional DCDC are optimized usingthe simplex optimization algorithm to obtain the optimumset of parameters for the control systems Section 2 brieflydescribes the system configuration and operation principleof the considered grid-connected PV with BES Section 3provides the modeling details of the PV and BES Section 4describes the proposed control strategies for the G-VSCand the bidirectional DCDC converter Section 5 discussesthe DC bus regulation strategy and the control parameteroptimization in detail Sections 6 and 7 present the simulatedresults and some concluding remarks respectively

2 System Configuration and Operation

The configuration of the considered single-stage grid-connected hybrid PVBES system is as shown in Figure 1The system consists of a PV array (PV gen) interfacedto the DC bus through a buck DCDC converter with amaximum power point tracking (MPPT) controller The G-VSC facilitates the MPPT operation through regulation ofthe DC bus voltage as well as transfer of power from theDC bus to the utility grid In addition the G-VSC providessynchronization of the PV systemwith the grid during startupor reconnection after system islanding

As can be seen from Figure 1 to enhance the DC busvoltage regulation BES is used where it is interfaced via abidirectional buck-boost converter (BES conv) which con-trols the chargedischarge processes during severe operatingconditions such as abrupt change in solar irradiation level andfault occurrences From the G-VSC AC output terminals thehybrid subsystem is connected to the utility grid at the PCCthrough a low-pass filter and an interconnection transformerthat is represented by an inductor These components areresponsible for filtering harmonics and isolating the entire

system from the utility grid The transformer steps up thevoltage level of the PV system from 023 kV to 11 kV line-to-line RMS voltageThe PVBES system injects total power 119875119866to the utility grid in which in this case the utility grid networkis based on a standard medium voltage distribution system[15]

3 System Modeling

This section provides the detailed models of the systemcomponents which are simulated using the PSCADEMTDCtransient simulator [16]

31 Modeling of PV Array The inclusion of the PV model inPSCADEMTDC is based on the Norton equivalent circuitgiven in Figure 2 [17] Assuming that the PV modules areof the same type and are subjected to similar environmentalconditions a PV arraymodel (Figure 2(b)) can be representedby a combination of series-connected 119873119904 and parallel-connected 119873119901 modules The current and resistance of suchPV array model are given by

119868eqarray = 119873119901119868eq = 119873119901119868119894119877119901

119877119904 + 119877119901

119877eqarray =119873119904

119873119901

119877eq =119873119904

119873119901

(119877119904 + 119877119901)

(1)

where 119877119904 and 119877119901 are the series and parallel resistanceof an ideal single diode PV cell model representing thestructural resistance and leakage current of the 119901-119899 junctionrespectively [18] 119868119894 is the terminal current of an ideal PVmodule derived from the ideal PV cell model which has thefollowing form [17]

119868119894 = 119868119892 [1198680 exp(120573

120572sdot

119877119901

119877119904 + 119877119901

(119881 + 119877119904119868)) minus 1] (2)

where 119868119892 is the cellrsquos photocurrent 1198680 is the dark current and120572 is the diode ideality factor 120573 is the inverse thermal voltagedefined as 120573(119879) = 119902119896119879 where 119902 is the electron charge 119896 isBoltzmannrsquos constant and 119879 is the 119901-119899 junction temperatureExcept for 120572 (assumed in this study as 15) all of the circuitparameters given in (2) are functions of the PV device typeobtained from the manufacturer datasheet [17 19]

32 Modeling of Lead-Acid Battery Many options are avail-able for the selection of a suitable battery model for a range ofapplications These options include the simple voltage sourcemodel the Thevenin model [20] generic models [21 22]and dynamic andmore realistic models [23 24] that considerthe nonlinear characteristics of battery parameters Howeverto avoid excessive complexity with the consideration of thedynamic behavior of the battery cell this study considered ageneric model described in [21] The model for the lead-acidbattery is constructed based on two important parametersnamely the terminal voltage 119881bat and state of charge SOC

The Scientific World Journal 3

Rest of network(utility grid)

AC load

DC

DC

DC

DC

DC

ACBES conv

G-VSC

DC-busPV convPV gen

BES

PCC

Buck convcontrol (MPPT)

Voltage-current-mode control(a) DC bus voltageregulation (d-axis)(b) Unity power factor orzero Q injections (q-axis)

Buckboost conv control(DC-bus voltage regulation)

Filter andinterconnection

transformer

PBES

PPVLf0

PG

PL

Figure 1 System configurationcontrol of the grid-connected PV with BES

Ieq

ReqV

I

(a)

Ieqarray

ReqarrayVpv

Ipv

(b)

Figure 2 Norton equivalent circuit of the (a) PV module and (b) PV array

which represent the behavior of the battery119881bat and SOC canbe calculated as functions of battery current 119868bat as follows

119881bat = 119864bat minus 119877int119868bat

SOC = 100(1 minusint 119868bat119889119905

119876bat)

(3)

where 119864bat is the open circuit voltage of the battery thatis modeled using a controlled voltage source calculated asfollows

119864bat = 1198640 minus 1198701 minus SOCSOC

119876 + 119860 exp minus119861 (1 minus SOC) 119876bat

(4)

In (3)ndash(4)119877int and119876bat are the battery internal resistance andcapacity respectively 1198640 represents the battery open circuitvoltage that lies between the fully charged voltage and theexponential voltage of the battery discharge curve 119870 is thepolarization voltage119860 is the exponential voltage and 119861 is theexponential capacity From (4) the model accounts for both

the normal voltage part and the exponential part representedby the second and third terms respectively Following theparameter extraction procedure provided in [21] all modelparameters can be extracted from themanufacturer dischargecurves which are available in the battery datasheet [25]

4 Control of Power Converters

As shown in Figure 1 the power converters are comprised ofthe DCDC buck converter G-VSC and BES DCDC buck-boost converter respectively Since G-VSC and BES DCDCbuck-boost controls directly influence the voltage regulationof PV system DC bus the control schemes are described indetail in the following subsections

41 G-VSC Control In general the aim of the G-VSC controlscheme is to control the active and reactive power transferbetween the PV system and the utility gridThe active currentcomponent (119889-axis) of the G-VSC is used to regulate theDC bus voltage of the PV system whereas the reactive


current component (119902-axis) is used to ensure that the systeminjects reactive power at approximately unity power factorThe general operation of the PV system has to follow theregulations stated in the IEEE 1547 and UL1741 which statesthat the PV inverter is only allowed to inject power at unitypower factor [26] The G-VSC control developed is basedon two different methods namely the voltage-mode [1] andcurrent-mode [17] controllers respectively

411 Voltage-Mode Control Figure 3 shows the detailed G-VSC circuit with the control block diagram based on thevoltage-mode control scheme The controller has meritssuch as reduced control complexity and low number ofcontrol loops [1] Since it is an open-loop control schemethe measures taken to protect the G-VSC valves againstinstantaneous over current or network faults are by limitingthe output references from PI controllers using the saturationblocks (limiter) shown in Figure 3(b) The principle forthe active 119875 and reactive 119876 power controls via G-VSC isexpressed as follows

119875 =119881pcc119881dc

119883119904

119898 sin (120575)

119876 =119881pcc

119883119904

[119881pcc minus 119898119881dc cos (120575)]

(5)

where 119881pcc is the output fundamental component voltage atthe PCC 119881dc is the DC bus voltage 119883119904 = 1205961198711198910 is the sumof inductances for filter inductance and coupling transformerinductance 120575 is the angle and 119898 is the modulation indexNotably based on the PWM principle the relationshipbetween the output fundamental component voltage at theG-VSC terminal119881pwm and the DC bus voltage can be expressedas 119881pwm = 119898119881dc 119875 and 119876 are proportional to 120575 and 119898respectively when 1198711198910 is optimally designed and 120575 is less than10∘ [27]This control strategy results in a simple voltage-modecontrol system design where active power is controlled by thevalue of 120575 and reactive power is regulated using119898 through PI1and PI2 respectively

As shown in Figure 3(b) PI1 generates a reference angle120575 for the PWMby processing the error of the DC bus voltageto ensure that the flow of power is constantly directed fromthe PV to the grid while regulating the DC bus voltageConsequently PI2 generates the output reference 119898 thatprocesses the error of reactive power from its reference valueand keeps the net power injected to the grid at the unity powerfactor (119876ref = 0) Importantly the value of 119898 is controlledto make it remain less than unity (ie the linear modulationregion) with the optimal value preferably close to unity toensure a reasonable efficient power conversion by the G-VSCThe output terminal voltage of G-VSC is regulated at 120596whichis the reference fundamental frequency at the PCC

412 Current-Mode Control The current-mode control is aclosed-loop current controlmethod inwhich the phase angleandmagnitude of theVSC terminal voltage are controlled in a119889-119902 rotating reference frame This control approach imposesdirect regulation on the G-VSC current which avoids the

vulnerability of G-VSC valves when they are subjected tolarge transient currents such as during network faults andabrupt load changes Referring to the G-VSC circuit shown inFigure 3(a) the control block diagram for the current-modecontrol scheme is as shown in Figure 4

As can be seen in Figure 4 a phase-locked loop (PLL) isutilized to extract the angle 120579 of the grid voltage that is to beused by the abc-to-dq0 or dq0-to-abc transformation blocksIn the PLL the PCC voltage vector (V119906-119886119887119888) is projected on the119889 and 119902 axes of the 119889-119902 frame and the 119889-119902 frame is rotatedin such a way that V119906119902 is forced to zero [17] Settling V119906119902 atzero makes the 119889-axis of the 119889-119902 frame aligned with the gridvoltage vector and the 119889-119902 frame rotational speed becomesequal to the grid angular frequency [1] Regarding this thesynchronization scheme based on PLL makes the value of 119875and 119876 proportional to and can be controlled by 119894119889 and 119894119902respectively as follows

119875 =3

2V119906119889119894119889

119876 = minus3

2V119906119889119894119902

(6)

In this case 119875 is represented as a DC bus voltage (119881dc) inwhich the processing of the 119881dc and 119876 errors is based onthe PI compensators (PI3 and PI4) to generate the referencecurrents 119894119889ref and 119894119902ref respectively which can be usedby the closed-loop current controller 119894119889ref and 119894119902ref can beexpressed as follows

119894119889ref = (1198961199011198893 + 11989611989411988931

119904) (119881dc minus 119881dcref)

119894119902ref = (1198961199011199024 + 11989611989411990241

119904) (119876 minus 119876ref)

(7)

where 119896119901 and 119896119894 are the proportional and integral gainsrespectively used in the PI3 and PI4 corresponding to 119889- and119902-axes components respectively

The current-mode control scheme within the inner cur-rent loop control of Figure 4 independently controls 119894119889and 119894119902 to make them rapidly track their respective currentcommands (119894119889ref and 119894119902ref) which can be represented in 119889-119902-frame equivalents as follows

1198711198910

119889119894119889

119889119905= 1205961198711198910119894119902 + 05119881dc119898119889 minus V119906119889

1198711198910

119889119894119902

119889119905= minus1205961198711198910119894119889 + 05119881dc119898119902 minus V119906119902

(8)

where 1198711198910 is the equivalent filter inductance that representsthe total inductance of the grid side filter and the transformerleakage reactance 119881dc is the DC bus voltage and 120596 is thegrid frequency It should be noted that the terms 05119881dc119898119889and 05119881dc119898119902 in (8) represent the G-VSC AC-side terminalvoltages V119905119889 and V119905119902 respectively in which 119898119889 and 119898119902 arethe corresponding 119889-axis and 119902-axis control inputs (PWMmodulation signals) while V119906119889 and V119906119902 are the exogenousinputs respectively [17]


G1G3G5

G4G6G2

VdcDC-bus

ta

tb

tc

Lf0

Idc

ua

ub

uc

PCC(Vpcc )

ita

itb

itc

P Q

(a)

120596

Carrier

Sin

+

Vdc ref

Q ref

PI1

PI2

Limitter

LimitterQm

Phase shift(120∘)

PWM

Vdc120575 G1

G3

G5

G4

G6

G2

minus

+

minus

u abcref-

(b)

Figure 3 G-VSC control scheme (a) G-VSC circuit and (b) voltage-mode controller

Outercontrol loop

Inner currentcontrol loop

+

minusVdc

Q

Vdcref

it abc

120579

abc

dq0

PI4

PI5

PI6

PI3idref

id

iq

iqref

Qref

+

minus +

minus

120596Lf0

120596Lf0

ed

eq uq

ud

md

mq

++

++

+

+

minus minus

udref

uqref

05Vdc

05Vdcabc

abc

dq0

dq0

120579

ud

uq

uq

Carrier

PWM

PLL

G1

G3

G5

G4

G6

G2

undashabc

ndash u abcrefndash

Figure 4 G-VSC control based on the current-mode scheme

Rearranging (8) and considering 119906119889 = 1198711198910119889119894119889119889119905 and119906119902 = 1198711198910119889119894119902119889119905 05119881dc119898119889 = V119906119889ref and 05119881dc119898119902 = V119906119902refyield the following

V119906119889ref = V119906119889 + 119906119889 minus 1205961198711198910119894119902

V119906119902ref = V119906119902 + 119906119902 + 1205961198711198910119894119889(9)

where V119906119889ref and V119906119902ref are the output voltage references fromthe current controller 119906119889 is the output of the compensator PI5(1198961199011198895 and 1198961198941198895) that processes the error signal of 119890119889 = 119894119889refminus119894119889and 119906119902 is the output of compensator PI6 (1198961199011199026 and 1198961198941199026) thatprocesses the error signal of 119890119902 = 119894119902ref minus 119894119902 The generatedreference modulation index from the current controllers119898119889

and 119898119902 is transformed back to the phase equivalents for useof the PWM generator using the dq0-to-abc transformationblock

42 BES DCDC Buck-Boost Converter Control Control ofthe chargingdischarging of BES is achieved by using abuck-boost converter circuit with two PI controllers asshown in Figure 5 where PI7 processes the DC bus voltagediscrepancies during disturbances to make the bus voltagefollow the voltage set point set as 119881dcref = 500VThe internalcurrent control loop is also adopted for the battery currentcontroller compensated by PI8The output signal from PI8 is


VbatIbat

VRLANP4-12batterymodel

+

Rint

Ebat

SOC

Reset

DCDC buck-boost conv

Ibat

minus

S1

Vdc

L2

S2Limitter

BES model

(a)

Com

S2

S1

Input sig

Vdc

SOC and Vdccontrol

SOC

Ibat ref

Ibat

PI7 PI8+

Vdcref

Vdc

+

Sw control logic

minus minus

(b)

Figure 5 BES buckboost converter control (a) converter circuit and (b) control scheme

passed to the PWM generation circuit where the logic circuitis used for the decisions including the charge discharge orhalt modes of operation The switch S1 is triggered and S2 iszero during the boost (discharge)mode and vice versa duringthe buck (charge) mode to absorb power from the DC busBoth S1 and S2 become zero (halt mode) when no regulationsignal is transferred

Figure 6 shows the algorithm developed for SOC and busvoltage control to ensure a secure and optimal operation ofBES The upper and lower limits of SOC denoted as SOC119867and SOC119871 are defined to avoid overcharge or deep dischargeof BES The upper and lower SOC levels avoid operation atexponential capacity region which may affect the magnitudeof current drawn at the battery terminal Preferably for lead-acid battery the recommended useable capacity should notexceed 70 of the total capacity especially when consideringcontinuous charge discharge operation [25] Consequentlythe upper and lower boundaries of theDCbus voltage controlare also considered to avoid unnecessary chargedischarge Inthis case the battery is set to chargedischarge only when thedeviation of DC bus voltage exceeds a certain range denotedas 119881dc119867 and 119881dc119871 respectively The algorithm utilizes theinput references of the SOC and the DC bus voltage wherethe output logic from the algorithm provides input for thecontrol logic circuit for determining the operatingmodes (seeFigure 5)

5 Optimal DC Bus VoltageRegulation Strategy

In conventional grid connected PV system without BES theregulation ofDCbus voltage is achieved solely through theG-VSC However with BES connected to the DC bus enhanced

control strategy can be achieved through regulation by bothG-VSC and BES buck-boost converters Regarding this it isimportant to develop an optimal control scheme to boost theregulation performances of these power converters so as tominimize the stress received along the DC bus during severedisturbance condition The effect of bus voltage fluctuationis related to power imbalance caused by fluctuations thatoriginate fromvarious sources of disturbances such as suddenchange of solar irradiation utility grid fault and load stepchange in the vicinity Such a power imbalance causes extraenergy Δ119864 which is related to the DC bus capacitor 119862dc asfollows

Δ119864 = int119879119904

Δ119875119889119905 =1

2119862dc (119881

2

dc1 minus 1198812

dc0) (10)

where 119881dc0 and 119881dc1 represent the DC voltage at the start andend of the period 119879119904 respectively and 119862dc is the total DCcapacitance In (10) 119862dc largely influences the variation inDC bus voltage and thus the response of the system com-pensators for DC bus voltage regulation must be sufficientlyfast

From Figure 5(b) the battery current reference 119868batreffor chargedischarge operation of buck-boost converter isprovided by PI7 in which the DC bus voltage is regulatedusing the compensator as follows

119868batref = (1198961199011198877 + 11989611989411988771

119904) (119881dcref minus 119881dc) (11)

where 1198961199011198877 and 1198961198941198877 are the control parametersTo improve voltage regulation so as to increase the

dynamic performance of the system the control parametersfor the BES DCDC converter and the G-VSC need to be


MeasureSOC Vdc

SOCL le SOC le SOCH

Vdc L le Vdc le VdcH

Boost(discharging)

Halt(no operation)

Halt(no operation)

Buck(charging)

No

Yes

Yes

No

Yes

No

No

Yes

SOC gt SOCH

Vdc gt VdcH

SOC lt SOCL

Vdc lt VdcL

Figure 6 Flowchart for SOC and BES power chargedischarge controls

optimized The conventional hand-tuning method of thePI controllers used for the control system is improved byusing the simplex optimization toolbox available in thePSCADEMTDC [28]

The simplex method is an optimization technique origi-nally devised by Nelder and Mead [29] and is based on geo-metric considerations The geometric figure whose verticesare defined by a set of 119899 +1 in an 119899-dimensional space is calledsimplex For example for two variables a simplex is a triangleThe simplex algorithm compares function values at the threevertices of the triangle where the worst vertex (eg the largestvalue for minimization problem) is discarded and replacedby a new one By iterative process a new triangle is formedand the search continues until the function values at thevertices become smaller and smaller The size of the triangleis thus reduced until the coordinates of the optimum pointare found [30] The advantage of this method is its simplicitywhich needs only objective function evaluations and does notrequire first and higher order derivatives such as the gradient-based methods [31] Moreover it is computationally compactand effective with good convergence properties for mostproblems with parameters to be optimized less than ten [32]The method is highly applicable for nonlinear multi-inputmultioutput systems without obtaining transfer function ormathematical formulation and hence suitable for findinglocal minimum of an objective function defined by severalvariables

In the present study the aim is to minimize the weightedintegral squared error (WISE) products of theDC bus voltagecontrolled by the G-VSC and the BES buck-boost converters

The considered performance index can be expressed in thefollowing general form

119882ISE = 1198821ISE1 +1198822ISE2 (12)

where1198821 and1198822 are the weighting factors used to signify therelative importance of the design specifications and ISE1 andISE2 are the partial indices used to penalize the deviation ofthe DC bus voltage [31] Based on the performance index in(12) the objective function to search for optimal parametersfor the PI controllers (ie PI1 PI3 and PI7) responsiblefor DC bus voltage regulation is formulated For examplethe objective function for the case of BES-based regulationtogether with current-mode control scheme of G-VSC isdescribed as follows

OF (xdc) = int1198791

1198790

1198821(119881dc minus 119881dcref)2119889119905

+ int

119879119865

1198791

1198822(119881dc minus 119881dcref)2119889119905

(13)

where xdc represents the control parameters for the PI3 andPI7 controller gains 1198790 is the time at which the reference ischanged within the entire length of the simulation time 119879119865and 1198791 is suitably selected intermediate point that permitsthe assignment of different weighting factors1198821 and1198822 tothe initial and later portions of the response The values of1198821 and1198822 are selected depending on the proportional andintegral gains selected during initial trial and error tuning ofthe PI controllers preferably1198821 gt 1198822 to ensure stability ofthe system


Table 1 PV module parameters

Model parameter Value Symbols [17]Cell type 610158401015840 multicrystalline silicon mdashNumber of cells and connections 60 in series mdashShort circuit current at aSTC 83 A 119868sc119903

Open circuit voltage at STC 367 V 119881oc119903

Maximum power current at STC 77A 119868mpp119903

Maximum power voltage at STC 292V 119881mpp119903

Current temperature coefficient 0004AK 119896119868

Voltage temperature coefficient minus01 VK 119896119881

Diode ideality factor 15 120572

Electron charge 1602 times 10minus19 C 119902

Boltzmannrsquos constant 1380 times 10minus23 JK 119896

aSTC standard test condition

6 Results And Discussion

The effectiveness of the proposed control strategies in com-parison to the conventional method is investigated throughsimulation in PSCADEMTDC Validation of the systemcomponent models is first given and then performancecomparison of the simulation results with and without use ofBES as well as with optimized control scheme is discussed

61 Model Validation Validation of the models is madeby comparing the steady state PV module 119868-119881 curves andthe BES discharge voltage curves respectively with thecorresponding manufacturer data

611 PVModel Theparameter extractionmethod for the PVmodel is based on [17] with key equations given in (1)ndash(2)Table 1 provides the parameter values of the PV module usedin the simulation of PV model in PSCADEMTDC

The results from the simulated modulersquos characteristiccurves are compared with the Hyundai SG-series multicrys-talline type solar module manufacturer datasheet [19] Fig-ure 7 shows the results of the comparison of the modulersquos 119868-119881characteristics simulated at standard test conditions (STCs)As can be seen in Figure 7 the simulated results (Figure 7(a))are comparedwell to the values in themanufacturer datasheet(Figure 7(b)) The modulersquos nominal power output is mea-sured approximately by 226W as shown in Figure 7(a) It isevident that the behavior of the simulated PVmodule currentincreases with the increase in solar irradiation at constanttemperature (25∘C) Consequently the voltage decreases withthe increase in the cellrsquos temperature when the irradiationis fixed at 100Wm2 Having validated the PV simulationmodel the PV modules are arranged in series land parallelconnections to formaPVarray (generator)ThePVgeneratorsize considered in the simulation is 215 kWpwhich is a typicalsize for grid-connected PV system found in residential areas

612 Battery Model An NPC series valve regulated leadacid namely the Yuasa VRLA NP4-12cell (12 V 4Ah) isconsidered suitable for the cyclic application of the battery

Table 2 Battery module parameters (12V 4Ah)

Model parameter Value Symbols [21]Cell type Lead-acid (VRLA) mdashNumber of cells per module 6 in series mdashRated capacity 4Ah 119876rated

Battery reserve 099Ah Bat resvNominal capacity 085Ah 119876nom

Exponential capacity 067 119876exp

Maximum voltage 1215 V 119864full

Exponential voltage 1205V 119864exp

Nominal voltage 12V 119864nom

Charge current 4A 119868chg

Internal resistance 004 119877int

Efficiency 80 EtaaSeries battery 1 119899119904aParallel battery 1 119899119901aIncreased combinations of 119899119904 and 119899119901 scales up the battery modules to forma BES

model [25] Parameter values of the battery module aredetailed in Table 2

Figure 8 shows a comparison of the 12V battery modulesimulation results with the battery data from the manufac-turer in terms of the terminal voltage behaviors versus dis-charge time The discharge currents ranging from 08 to 4Ahave been simulated as shown in Figure 8(a) From the figureall the discharge current curves of the simulated batterymodule are generally in good agreement with the standardmanufacturerrsquos discharge test data [25] From Figure 8(b) bysuperimposing the voltage curve of 02times119862bat ampere (08 A)the curve matches very well with the actual test curve duringalmost 80 of the discharge

The BES simulation was developed by increasing 119899119904 and119899119901 values that is the series and parallel arrangement of thebattery modulersquos matrix In the simulation a total of 48 kWhBES was used which can be arranged from approximately20 series connected battery modules with 50 parallel stringsThe BES output terminal voltage is around 240V and it is


0 10 20 30 400

2

4

6

8

10

Voltage (V)

Curr

ent (

A)

0

50

100

150

200

250

Pow

er (W

)G = 700Wm2

G = 800Wm2

G = 900Wm2

G = 1000Wm2

G = 1100Wm2

Pmpp

T = 65∘CT = 45∘C

T = 25∘CT = 5∘C

0 10 20 30 400

2

4

6

8

10

Voltage (V)

Curr

ent (

A)

(a)

0 5 10 15 20 25 30 35 400

1

2

3

4

5

6

7

8

9

10

Voltage (V)

Curr

ent (

A)

0 5 10 15 20 25 30 35 400

1

2

3

4

5

6

7

8

9

10

Voltage (V)

Curr

ent (

A)

Cell temp = 25∘CIncid irrad = 1100Wm2

Incid irrad = 1000Wm2





Operating cell temp = 5∘COperating cell temp = 25∘C


(b)

Figure 7 Comparison of the PV module 119868-119881 curves (a) simulated Hyundai M224SG and (b) manufacturer data

interfaced with the DCDC buck-boost converter that canstep up the voltage to 500V during boost mode The batterybank is considered suitable for intermittent discharge tocompensate for DC bus voltage discrepancies [28]

62 Simulation Results The DC bus voltage regulation per-formance was evaluated by considering with and withoutthe use of BES The simulation parameters are as shown inTable 3

621 Evaluation of the Voltage-Mode Control Scheme ofG-VSC Figure 9 shows the dynamic performance of thePVBES system being subjected to critical a condition ofplusmn50 step change of irradiation and a voltage sag at the PCCAs shown in Figure 9(a) an abrupt change in irradiation isapplied at 2 s and lasted for 05 s which causes the array powerto drop suddenly about 50 Similarly in Figure 9(b) whena voltage sag is applied at 3 s for a duration of 05 s the PCCRMS voltage is found to be 55 kV hence causing a 50 dropfrom the nominal 11 kV value


100 101 102 103

8

9

10

11

12

13

Discharge time (min)Te

rmin

al v

olta

ge (V

)

02 times C Amps04 times C Amps


(a)

1 2 4 6 8 10 20 40 60 2 4 6 8 10 20

Discharge time

40

45

50

55

60

65

(V)For 6Vbattery

(V)

batteryFor 12V

80

90

100

110

120

130

Term

inal

vol

tage

3

2

106

0402 01

005

NP AT 25∘C (77 )

(min) Hours

∘F

CACA

CACA

CACA CA CA

(b)

Figure 8 Comparison of the battery module discharge curves at different current magnitudes (a) simulated Yuasa NP4-12 discharge curveand (b) manufacturer data of the Yuasa NP series battery (note that battery modulersquos capacity lowast119862 = 119862bat = 4Ah) Note 119862 given capacity asstated on each battery in Ah

Overall as can be observed from the DC bus voltageprofile of Figure 9(c) voltage fluctuation decreases whenBES is connected as evident from the variation of transientpeak surges and the corresponding transient settling timesWithout BES the transient spikes are measured around 10ndash108 and 20ndash232 (sag and spike) during irradiationdisturbance and utility grid fault respectively Howeverwhen BES is connected the spikes and sag are reduced to66ndash74 and 132ndash18 (spikes with sag around 64)respectively These results imply that the BES compensationfor transient overshoot and undershoot at the DC bus voltageresults in minimal power fluctuation for the total powerdelivered to the utility grid (see Figure 9(d))

Severe disturbance such as utility grid fault preventsthe voltage-mode control method for the G-VSC to restorethe DC bus voltage to its reference 500V value causingsubsequent voltage sag for approximately 20 without BESWith BES connected the voltage regulation is improved

to a certain degree of approximately 64 sag because ofthe compensation through the BES converter As shownin Figure 9(d) for the reactive power control BES can-not overcome poor regulation of the voltage-mode controlscheme thus causing fluctuation of the reactive power duringboth disturbance conditions This is due to the fact thatBES compensation in this case only applies for active powerregulation

During the simulation period of Figure 9 the BES outputpower and SOC profiles are recorded as shown in Figures10(a) and 10(b) respectively The switching states of theDCDC buck-boost converter during regulation service arealso shown in Figure 10(c)

As shown in Figures 10(a) and 10(b) BES discharged andcharged its power to compensate for the DC bus voltagefluctuation thus causing decreaseincrease of SOC at 2 sand 25 s respectively However more power is dischargedduring utility grid fault causing SOC to drop about 9


Table 3 Simulation parameters

Model parameter Value Symbolscomments

PV system 200 kWp 119875PV

BES system 48 kWh 119875BES

BES terminal voltage 240V 119881bes

BES total capacity 200Ah 119862bes

System loads 100 kW 119875119871

PCC system voltage 11 kV 119881pcc119871119871 119877119872119878

G-VSC AC side voltage 023 kV 119881119905119871119871 119877119872119878

DC bus voltage 500V 119881dc

Capacitor 10000 uF 50000 uF 119862PV 119862dc

Inductor 10mH 012mH 04mH 1198711 1198712 1198711198910

Transformer (TR1) 01MVA 01 pu Rating and leakage inductancePI1 PI2 controller gains (G-VSC voltage mode) 1 0005 02 1 119896pdc1 119896idc1 119896pq2 119896iq2

PI3 PI4 PI5 PI6 controller gains (G-VSC current mode) 2 0001 06 00501 20 5 005

119896pd3 119896id3 119896pq4 119896iq4 119896pd5 119896id5 119896pq6 119896iq6

PI7 PI8 controller gains (BES DCDC converter) 12 02 1 05 119896pb7 119896ib7 1198961199018 1198961198948

SOC limits Max 095 puMin 05 pu

aSOC119867 SOC119871

119881dc limits Max 0525Min 0475

b119881dc119867 119881dc119871

Switching frequency 2500Hz DCDC (MPPTbuck-boost) and G-VSCSimulation time step and running duration 005ms 4 s Δ119905 119879119865

aMaximum 45 useable capacity b5 119881dc droop characteristic

(see Figure 10(b)) in order to restore the resultant 20 dropof voltage of the DC bus in between 3 s and 35 s It is evidentthat although BES can slightly improve DC bus voltageregulation in the cases discussed the voltage-mode controlscheme of G-VSC shows poor performance and needs extraenergy from the BES in order to enhance the DC bus voltageregulation

622 Evaluation of the Current-Mode Control Scheme of G-VSC The performance of PVBES system using the current-mode control scheme of G-VSC is evaluated based onthe similar disturbance conditions as previously discussedFigure 11 shows the overall system performance for the caseswith and without BES

From Figure 11 it is evident that the closed-loop controlresponse of the current-mode scheme is relatively faster thanthat of the open-loop voltage-mode control scheme The DCbus voltage profile as shown in Figure 11(a) is improvedeven without BES connected to the DC bus with 64ndash68maximum spikes during irradiation step change and 82ndash102 range of spikes during utility grid fault No voltagesag is observed during the latter disturbance conditionWhen BES is connected the voltage profiles in terms oftransient peaks and settling times (Figure 11(a)) are improvedwith only approximately 42ndash48 and 58ndash82 range ofspikes during irradiation disturbance and utility grid fault

respectively The results indicate the capability of BES inperforming DC bus voltage regulation

Overall comparison of the voltage-mode and current-mode control performances reveals that regulation by usingthe current-mode control scheme is superior particularlywhen the system is subjected to utility grid faults A morestable and fast response of system controller can be seenfor the current-mode control method between 3 s and 35 ssimulations as shown in Figures 11(a) and 11(b) It is importantto note in Figure 11(b) that no change is observed for reactivepower regulation with or without BES because BES is onlyset to compensate the bus voltage discrepancies using itsactive power while G-VSC reactive power control works atunity power factor However it is obvious that reactive powerregulation through current-mode control scheme of G-VSCis relatively better compared to the voltage-mode controlscheme in controlling constant zero reactive power injectionto the utility grid

Figure 12 shows the BES power and SOC profiles withthe corresponding switching states of the DCDC buck-boost converter It is evident that improvement in systemstability ensures optimal chargingdischarging through theBES converter in which minimum power from batteriesis consumedreleased during compensation as shown inFigure 12(a) Small changes in SOC (Figure 12(b)) at theinstant of disturbances applied indicate that the BES can beresized to a more optimal size which can be much smaller


15 2 25 3 35 4

0102

Time (s)

Pow

er (k

W)

Ppv

(a)

15 2 25 3 35 4

Time (s)

5

10

Volta

gePC

C (k

V)

Vpcc rms

(b)

15 2 25 3 35 4

Time (s)

040506

20 sag

Volta

ge D

Cbu

s (kV

)

Vdc bes offVdc bes on

(c)

15 2 25 3 35 4

Time (s)

minus0101

Pow

er (k

W)

and

(kVA

R)

Pg bes offPg bes on

Qg bes offQg bes on

(d)

Figure 9 Results of DC bus voltage regulation and active andreactive power profiles for the case with and without BES and usingvoltage-mode controlled G-VSC

Overall simulation results show that a combination of BESwith current-mode control of G-VSC can provide superiorDC bus voltage control performance of the grid-connectedPV system

623 Results of DC Bus Voltage Regulation Using SimplexOptimized Control Schemes To compare the effectiveness ofthe proposed optimized control scheme with the traditionalhand-tuning method of the power converters several sim-ulation cases were considered for the voltage- and current-mode controlled G-VSC with BES connected to the DC busThe results of the parametric optimization problem usingthe voltage-mode and current-mode control schemes are asshown in Figure 13 From the figure the objective functionthat is the WISE performance index of the DC bus voltagedeviations has been reduced and the parameters becomeoptimal after less than 100 numbers of iterations

From the simulation results of Figure 13 a summary of theoptimized control parameters used for the power convertersdescribed in Figure 1 is shown in Table 4

15 2 25 3 35 4minus50

0

50

Time (s)

Pow

er (k

W)

DischargingCharging

Pbes

(a)

15 2 25 3 35 4

Time (s)

60

64

68

SOC

()

SOC

More power discharge

(b)

15 2 25 3 35 4

Time (s)

minus15minus050515

Pulse

s (p

u)

S1

S2

Buck modeBoost mode

(c)

Figure 10 BES profiles during voltage regulationwith voltage-modecontrol scheme of G-VSC

Using the optimized controller gains shown in Table 4simulations were carried out to compare the DC bus voltageregulation performance of the cases with BES using voltage-mode and current-mode controlled G-VSC Figure 14 showsthe simulation results for the purpose of the comparison Ingeneral it is evident that with optimized control schemesthe DC bus voltage can be further regulated at a certain levelproviding a more stable DC bus voltage over the period ofvarying disturbances conditions As shown in Figure 14(a)when the system is subjected to changing atmospheric con-ditions the optimized controller of the voltage-mode schemecan fairly improve voltage regulation The undesired spikesare reduced from the range 66ndash74 to 246ndash27 at 2 sand 25 s respectively However during voltage sag at thePCC the DC bus voltage cannot be restored to its referencevalue Again this can be attributed to poor regulation of thevoltage-mode control scheme which was based on the open-loop voltage control strategy [1] Another reason is that BESoperation is subjected to a maximum BES current discharge(eg at maximum of 1 times 119862bes rate) in order to ensure safeoperation so as to obey the current rating of the BES DCDCconverter

However with current-mode control scheme as shownin Figure 14(b) the optimized control parameters can sig-nificantly increase the regulation performance The mea-sured voltage spikes over the period of simulation are verymarginal From the figure the voltage spikes have beenreduced from the range 42ndash48 to 182ndash196 duringirradiation disturbance and from 58ndash82 to 212ndash296


Table 4 Initial and optimised PI controller gains for the power converters based on simplex optimum run

Power converter Compensator Hand tuning aOptimized119896119901 119896119894 119896119901 119896119894

G-VSC (voltage mode) PI1 1 0005 1015 00008713PI2 02 1 02 1

G-VSC (current mode)

PI3 2 0001 1957 00002511PI4 06 0005 06 0005PI5 01 20 01 20PI6 5 005 5 005

DCDC buck-boost (BES)PI7 (voltage-mode) 12 02 1147 02438PI7 (current-mode) 12 02 1212 02026

PI8 1 05 1 05aMinimize WISE performance index with1198821 = 0071198822 = 0008 total number of runs = 200

15 2 25 3 35 404040605

06

Time (s)

Volta

ge D

Cbu

s (kV

)


(a)

minus010

0102

Pow

er (k

W)

and

(kVA

R)

15 2 25 3 35 4

Time (s)

Pg bes offPg bes on

Qg bes offQg bes on

(b)

Figure 11 Results of DC bus voltage regulation and active andreactive power profiles for the case with and without BES and usingcurrent-mode controlled G-VSC

when voltage sag occurs at the PCC This can significantlyimprove the performance of the G-VSC operation since theinput voltage DC bus is now more stable and constant thuscontributing to minimizing loss of power within the powerconverter and a robust control system design

7 Conclusion

This paper presented an assessment of the optimal controlfor DC bus voltage regulation by using a voltage-sourcedconverter (VSC) and a battery energy storage (BES) DCDCbuck-boost converter The voltage-mode control method hasa low number of control loops compared to the current-mode control scheme making it simple in practice How-ever the poor regulation performance of the voltage-modecontrol method results in greater energy requirement of

15 2 25 3 35 4minus50

0

50

Time (s)Po

wer

(kW

)

Pbes

(a)

15 2 25 3 35 4

Time (s)

68

69

SOC

()

SOC

(b)

15 2 25 3 35 4

Time (s)

minus15minus050515

Pulse

s (p

u)

S1S2

(c)

Figure 12 BES profiles during voltage regulation service of thesystem with current-mode control scheme of G-VSC

batteries for compensation which consequently increasesstorage cost Using the BES compensation and voltage-mode controlled G-VSC the DC bus voltage fluctuated atapproximately 66 to 74 and 132 to 18 during the50 step changes in the irradiation and utility grid faults(voltage sags) respectively On the other hand the overallperformance was improved using the current mode controlscheme with fluctuations minimized to the range of 42to 48 and 58 to 82 in the irradiation and utility gridfaults (voltage sags) respectively Moreover the latter casecauses no voltage sag to occur at the DC bus during the utility


0 50 100 150 200

Number of runs

0

005

01

OF

(vol

tage

-mod

e)

0

05

1

OF

(cur

rent

-mod

e)

05

1

15

2

1

2

3

minus05

0

05

1

minus05

0

05

1

1

15

2

1

15

2

0 50 100 150 2000

05

1

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0

05

1

X 125Y 02026

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

(j)

(h)

kpdc1

kpd3

kidc1

kid3

kpb7

kpb7

kib7

kib7

Figure 13 Optimization results of the BES control parameters and the parameters of voltage-mode and current-mode control schemes thatare responsible for DC bus voltage regulation

15 2 25 3 35 4035

045

055

065

Time (s)

Volta

ge (k

V)

Vdc voltage-mode (hand-tuning)Vdc voltage-mode (optimised)

(a)

15 2 25 3 35 4

Time (s)

035

045

055

065

Volta

ge (k

V)

Vdc current-mode (hand-tuning)Vdc current-mode (optimised)

(b)

Figure 14 Comparison of DC bus voltage profiles for the cases without and with optimized control parameters (a) voltage mode and (b)current mode

grid fault These results can be attributed to the capabilityDC-coupled BES to restore DC bus voltage to 1 pu quicklyFurthermore using the optimized current-mode controlscheme the DC bus voltage overshoot and undershoot onlyfluctuated in approximately 182 to 296 range during

all disturbance cases Overall the results show that theproposed optimizationmethod for PI control parameters cancontribute to the optimal control of the power convertersof the PVBES system and improve the overall systemefficiency


Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

This work is supported by Universiti Kebangsaan Malaysiaunder the research Grants ERGS12012TK02UKM013 andDIP-2012-30 Scholarships provided by Universiti MalaysiaTerengganu and theMinistry of EducationMalaysia are alsogratefully acknowledged

References

[1] A Yazdani and R Iravani Voltage-Sourced Converters in PowerSystems John Wiley amp Sons Hoboken NJ USA 2010

[2] N A Ahmed A K Al-Othman and M R AlrashidildquoDevelopment of an efficient utility interactive combinedwindphotovoltaicfuel cell power system with MPPT and DCbus voltage regulationrdquo Electric Power Systems Research vol 81no 5 pp 1096ndash1106 2011

[3] A Hajizadeh and M A Golkar ldquoControl of hybrid fuelcellenergy storage distributed generation system against volt-age sagrdquo International Journal of Electrical Power and EnergySystems vol 32 no 5 pp 488ndash497 2010

[4] M A Tankari M B Camara B Dakyo and C Nichita ldquoUltra-capacitors and batteries integration for power fluctuationsmiitigation in windPVdiesel hybrid systemrdquo InternationalJournal of Renewable Energy Research vol 1 pp 86ndash95 2011

[5] M Zalani Daud A Mohamed and M A Hannan ldquoA reviewof the integration of energy storage systems for utility gridsupportrdquo Przeglad Elektrotechniczny vol 10 pp 185ndash191 2012

[6] X TanQ Li andHWang ldquoAdvances and trends of energy stor-age technology in Microgridrdquo International Journal of ElectricalPower amp Energy Systems vol 44 pp 179ndash191 2013

[7] K J Astrom and T Hagglund PID Controllers Theory Designand Tuning The Instrumentation Systems and AutomationSociety Philadelphia Pa USA 1995

[8] L Wang and N Ertugrul ldquoSelection of PI compensator param-eters for VSC-HVDC system using decoupled control strategyrdquoin Proceedings of the 20th Australasian Universities PowerEngineering Conference pp 1ndash7 Christchurch New ZealandDecember 2010

[9] D C Das A K Roy and N Sinha ldquoGA-based frequencycontroller for solar thermal-diesel-wind hybrid energy gen-erationenergy storage systemrdquo Electrical Power and EnergySystems vol 43 pp 262ndash279 2012

[10] F D Bianchi A Egea-Alvarez A Junyent-Ferre andO Gomis-Bellmunt ldquoOptimal control of voltage source converters underpower system faultsrdquo Control Engineering Practice vol 20 no5 pp 539ndash546 2012

[11] A Luo Z Shuai W Zhu and Z J Shen ldquoCombined system forharmonic suppression and reactive power compensationrdquo IEEETransactions on Industrial Electronics vol 56 no 2 pp 418ndash4282009

[12] A M Vural and K C Bayindir ldquoOptimization of parameterset for STATCOM control systemrdquo in Proceedings of the IEEEPES Transmission and Distribution Conference and Exposition

Smart Solutions for aChangingWorld pp 1ndash6Orleans LaUSAApril 2010

[13] D R Northcott S Filizadeh and A R Chevrefils ldquoDesign ofa bidirectional buck-boost dcdc converter for a series hybridelectric vehicle using PSCADEMTDCrdquo in Proceedings of the5th IEEE Vehicle Power and Propulsion Conference (VPPC rsquo09)pp 1561ndash1566 Dearborn Mich USA September 2009

[14] S Filizadeh A R Chevrefils andD R Northcott ldquoAnalysis anddesign of vehicular power systems using PSCADEMTDCrdquo inProceedings of the IEEEVehicle Power and PropulsionConference(VPPC rsquo07) pp 463ndash468 Arlington Tex USA September 2007

[15] K Strunz ldquoBenchmark systems for network integration ofrenewable and distributed energy resourcesrdquo Cigre Task ForceC60402

[16] C Muller and R Jayasinghe PSCADEMTDC Userrsquos GuideManitoba HVDC Research Centre 2010

[17] A Yazdani A R di Fazio H Ghoddami et al ldquoModelingguidelines and a benchmark for power system simulationstudies of three-phase single-stage photovoltaic systemsrdquo IEEETransactions on Power Delivery vol 26 no 2 pp 1247ndash12642011

[18] R C Neville Energy Conversion The Solar Cell Elsevier NewYork NY USA 1995

[19] Hyundai Solar ldquoHyundai SG-series solar modulerdquo 2011[20] C-J Zhan X GWu S Kromlidis et al ldquoTwo electrical models

of the lead-acid battery used in a dynamic voltage restorerrdquo IEEEProceedings Generation Transmission and Distribution vol 150no 2 pp 175ndash182 2003

[21] O Tremblay L-A Dessaint and A-I Dekkiche ldquoA genericbattery model for the dynamic simulation of hybrid electricvehiclesrdquo in Proceedings of the IEEE Vehicle Power and Propul-sion Conference (VPPC rsquo07) pp 284ndash289 Arlington Tex USASeptember 2007

[22] J B Copetti F Lorenzo and F Chenlo ldquoA general batterymodelfor PV system simulationrdquo Progress on Photovoltaics Researchand Application vol 1 pp 283ndash292 1993

[23] S Barsali and M Ceraolo ldquoDynamical models of lead-acidbatteries implementation issuesrdquo IEEE Transactions on EnergyConversion vol 17 no 1 pp 16ndash23 2002

[24] M Ceraolo ldquoNew dynamical models of lead-acid batteriesrdquoIEEETransactions on Power Systems vol 15 no 4 pp 1184ndash11902000

[25] Yuasa Battery ldquoYuasa NP valve regulated lead-acid batterymanualrdquo 1999

[26] Y Liu J Bebic B Kroposki J de Bedout andWRen ldquoDistribu-tion system voltage performance analysis for high-penetrationPVrdquo in Proceedings of the IEEE Energy 2030 Conference pp 1ndash8Atlanta Ga USA November 2008

[27] S Peng G Shi Y Cao and X Cai ldquoVoltage and frequencycontrol of an islanded power system based on wind-batterygenerationrdquo International Review of Electrical Engineering vol6 no 4 pp 2002ndash2012 2011

[28] M Zalani Daud A Mohamed M Z C Z Wanik andM A Hannan ldquoPerformance evaluation of grid-connectedphotovoltaic systemwith battery energy storagerdquo in Proceedingsof the IEEE Conference on Power and Energy (PECON rsquo12) pp396ndash401 2012

[29] J A Nelder and R A Mead ldquoA simplex method for functionminimizationrdquoComputer Journal vol 7 no 4 pp 308ndash313 1965


[30] H M John and D F Kurtis Numerical Methods Using MatlabPrentice Hall New York NY USA 2004

[31] A M Gole S Filizadeh R W Menzies and P L WilsonldquoElectromagnetic transients simulation as an objective functionevaluator for optimization of power system performancerdquo inProceedings of the International Conference on Power SystemTransients (IPST rsquo03) pp 1ndash6 2003

[32] A M Gole S Filizadeh and P L Wilson ldquoInclusion ofrobustness into design using optimization-enabled transientsimulationrdquo IEEE Transactions on Power Delivery vol 20 no3 pp 1991ndash1997 2005

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and the integral gain 119896119894 respectively From the literatureseveral conventional tuning strategies that have been in useinclude the hand tuning or trial and error Smith Ziegler-Nichols and pole placement methods [7] However thesetuning strategies require the determination of system transferfunction which makes the method more complex [8] Anumber of optimization methods have been developed forfine-tuning converter control parameters [9 10] but onlyfew applications used the simplex algorithm From previ-ous studies applications of the simplex algorithm are incontrolling FACTS devices [11 12] and vehicular controlsystems that employ bidirectional converters [13 14] Thispaper addresses the issue of improving DC bus voltageregulation by using G-VSC and BES with a bidirectionalDCDC buck-boost converter for the efficient performanceof grid-connected PV systems The BES connected to theDC bus of the PV system can enhance the systemrsquos dynamicperformance by controlling the chargingdischarging of BESwith a bidirectional converter when the system is subjectedto varying disturbances The optimal controls of the G-VSCand the bidirectionalDCDCconverter are investigated in theproposed control methodologies First the control methodsof the G-VSC namely the voltage-mode and current-modecontrols are assessed Second the control parameters of theG-VSC and the bidirectional DCDC are optimized usingthe simplex optimization algorithm to obtain the optimumset of parameters for the control systems Section 2 brieflydescribes the system configuration and operation principleof the considered grid-connected PV with BES Section 3provides the modeling details of the PV and BES Section 4describes the proposed control strategies for the G-VSCand the bidirectional DCDC converter Section 5 discussesthe DC bus regulation strategy and the control parameteroptimization in detail Sections 6 and 7 present the simulatedresults and some concluding remarks respectively

2 System Configuration and Operation

The configuration of the considered single-stage grid-connected hybrid PVBES system is as shown in Figure 1The system consists of a PV array (PV gen) interfacedto the DC bus through a buck DCDC converter with amaximum power point tracking (MPPT) controller The G-VSC facilitates the MPPT operation through regulation ofthe DC bus voltage as well as transfer of power from theDC bus to the utility grid In addition the G-VSC providessynchronization of the PV systemwith the grid during startupor reconnection after system islanding

As can be seen from Figure 1 to enhance the DC busvoltage regulation BES is used where it is interfaced via abidirectional buck-boost converter (BES conv) which con-trols the chargedischarge processes during severe operatingconditions such as abrupt change in solar irradiation level andfault occurrences From the G-VSC AC output terminals thehybrid subsystem is connected to the utility grid at the PCCthrough a low-pass filter and an interconnection transformerthat is represented by an inductor These components areresponsible for filtering harmonics and isolating the entire

system from the utility grid The transformer steps up thevoltage level of the PV system from 023 kV to 11 kV line-to-line RMS voltageThe PVBES system injects total power 119875119866to the utility grid in which in this case the utility grid networkis based on a standard medium voltage distribution system[15]

3 System Modeling

This section provides the detailed models of the systemcomponents which are simulated using the PSCADEMTDCtransient simulator [16]

31 Modeling of PV Array The inclusion of the PV model inPSCADEMTDC is based on the Norton equivalent circuitgiven in Figure 2 [17] Assuming that the PV modules areof the same type and are subjected to similar environmentalconditions a PV arraymodel (Figure 2(b)) can be representedby a combination of series-connected 119873119904 and parallel-connected 119873119901 modules The current and resistance of suchPV array model are given by

119868eqarray = 119873119901119868eq = 119873119901119868119894119877119901

119877119904 + 119877119901

119877eqarray =119873119904

119873119901

119877eq =119873119904

119873119901

(119877119904 + 119877119901)

(1)

where 119877119904 and 119877119901 are the series and parallel resistanceof an ideal single diode PV cell model representing thestructural resistance and leakage current of the 119901-119899 junctionrespectively [18] 119868119894 is the terminal current of an ideal PVmodule derived from the ideal PV cell model which has thefollowing form [17]

119868119894 = 119868119892 [1198680 exp(120573

120572sdot

119877119901

119877119904 + 119877119901

(119881 + 119877119904119868)) minus 1] (2)

where 119868119892 is the cellrsquos photocurrent 1198680 is the dark current and120572 is the diode ideality factor 120573 is the inverse thermal voltagedefined as 120573(119879) = 119902119896119879 where 119902 is the electron charge 119896 isBoltzmannrsquos constant and 119879 is the 119901-119899 junction temperatureExcept for 120572 (assumed in this study as 15) all of the circuitparameters given in (2) are functions of the PV device typeobtained from the manufacturer datasheet [17 19]

32 Modeling of Lead-Acid Battery Many options are avail-able for the selection of a suitable battery model for a range ofapplications These options include the simple voltage sourcemodel the Thevenin model [20] generic models [21 22]and dynamic andmore realistic models [23 24] that considerthe nonlinear characteristics of battery parameters Howeverto avoid excessive complexity with the consideration of thedynamic behavior of the battery cell this study considered ageneric model described in [21] The model for the lead-acidbattery is constructed based on two important parametersnamely the terminal voltage 119881bat and state of charge SOC



AC load

DC

DC

DC

DC

DC

ACBES conv

G-VSC

DC-busPV convPV gen

BES

PCC





transformer

PBES

PPVLf0

PG

PL


Ieq

ReqV

I

(a)

Ieqarray

ReqarrayVpv

Ipv

(b)




SOC = 100(1 minusint 119868bat119889119905

119876bat)

(3)




(4)









119875 =119881pcc119881dc

119883119904

119898 sin (120575)

119876 =119881pcc

119883119904

[119881pcc minus 119898119881dc cos (120575)]

(5)






119875 =3

2V119906119889119894119889

119876 = minus3

2V119906119889119894119902

(6)


119894119889ref = (1198961199011198893 + 11989611989411988931

119904) (119881dc minus 119881dcref)

119894119902ref = (1198961199011199024 + 11989611989411990241

119904) (119876 minus 119876ref)

(7)



1198711198910

119889119894119889

119889119905= 1205961198711198910119894119902 + 05119881dc119898119889 minus V119906119889

1198711198910

119889119894119902

119889119905= minus1205961198711198910119894119889 + 05119881dc119898119902 minus V119906119902

(8)



G1G3G5

G4G6G2

VdcDC-bus

ta

tb

tc

Lf0

Idc

ua

ub

uc

PCC(Vpcc )

ita

itb

itc

P Q

(a)

120596

Carrier

Sin

+

Vdc ref

Q ref

PI1

PI2

Limitter

LimitterQm

Phase shift(120∘)

PWM

Vdc120575 G1

G3

G5

G4

G6

G2

minus

+

minus

u abcref-

(b)


Outercontrol loop


+

minusVdc

Q

Vdcref

it abc

120579

abc

dq0

PI4

PI5

PI6

PI3idref

id

iq

iqref

Qref

+

minus +

minus

120596Lf0

120596Lf0

ed

eq uq

ud

md

mq

++

++

+

+

minus minus

udref

uqref

05Vdc

05Vdcabc

abc

dq0

dq0

120579

ud

uq

uq

Carrier

PWM

PLL

G1

G3

G5

G4

G6

G2

undashabc

ndash u abcrefndash



V119906119889ref = V119906119889 + 119906119889 minus 1205961198711198910119894119902

V119906119902ref = V119906119902 + 119906119902 + 1205961198711198910119894119889(9)





VbatIbat


+

Rint

Ebat

SOC

Reset


Ibat

minus

S1

Vdc

L2

S2Limitter

BES model

(a)

Com

S2

S1

Input sig

Vdc

SOC and Vdccontrol

SOC

Ibat ref

Ibat

PI7 PI8+

Vdcref

Vdc

+

Sw control logic

minus minus

(b)







Δ119864 = int119879119904

Δ119875119889119905 =1

2119862dc (119881

2

dc1 minus 1198812

dc0) (10)



119868batref = (1198961199011198877 + 11989611989411988771

119904) (119881dcref minus 119881dc) (11)




MeasureSOC Vdc

SOCL le SOC le SOCH


Boost(discharging)

Halt(no operation)

Halt(no operation)

Buck(charging)

No

Yes

Yes

No

Yes

No

No

Yes

SOC gt SOCH

Vdc gt VdcH

SOC lt SOCL

Vdc lt VdcL






119882ISE = 1198821ISE1 +1198822ISE2 (12)


OF (xdc) = int1198791

1198790

1198821(119881dc minus 119881dcref)2119889119905

+ int

119879119865

1198791

1198822(119881dc minus 119881dcref)2119889119905

(13)


































0 10 20 30 400

2

4

6

8

10

Voltage (V)

Curr

ent (

A)

0

50

100

150

200

250

Pow

er (W

)G = 700Wm2

G = 800Wm2

G = 900Wm2

G = 1000Wm2

G = 1100Wm2

Pmpp

T = 65∘CT = 45∘C

T = 25∘CT = 5∘C

0 10 20 30 400

2

4

6

8

10

Voltage (V)

Curr

ent (

A)

(a)

0 5 10 15 20 25 30 35 400

1

2

3

4

5

6

7

8

9

10

Voltage (V)

Curr

ent (

A)

0 5 10 15 20 25 30 35 400

1

2

3

4

5

6

7

8

9

10

Voltage (V)

Curr

ent (

A)









(b)






100 101 102 103

8

9

10

11

12

13


rmin

al v

olta

ge (V

)



(a)

1 2 4 6 8 10 20 40 60 2 4 6 8 10 20

Discharge time

40

45

50

55

60

65

(V)For 6Vbattery

(V)

batteryFor 12V

80

90

100

110

120

130

Term

inal

vol

tage

3

2

106

0402 01

005

NP AT 25∘C (77 )

(min) Hours

∘F

CACA

CACA

CACA CA CA

(b)



















Inductor 10mH 012mH 04mH 1198711 1198712 1198711198910






aSOC119867 SOC119871


b119881dc119867 119881dc119871










15 2 25 3 35 4

0102

Time (s)

Pow

er (k

W)

Ppv

(a)

15 2 25 3 35 4

Time (s)

5

10

Volta

gePC

C (k

V)

Vpcc rms

(b)

15 2 25 3 35 4

Time (s)

040506

20 sag

Volta

ge D

Cbu

s (kV

)


(c)

15 2 25 3 35 4

Time (s)

minus0101

Pow

er (k

W)

and

(kVA

R)

Pg bes offPg bes on

Qg bes offQg bes on

(d)





15 2 25 3 35 4minus50

0

50

Time (s)

Pow

er (k

W)

DischargingCharging

Pbes

(a)

15 2 25 3 35 4

Time (s)

60

64

68

SOC

()

SOC


(b)

15 2 25 3 35 4

Time (s)

minus15minus050515

Pulse

s (p

u)

S1

S2

Buck modeBoost mode

(c)









PI3 2 0001 1957 00002511PI4 06 0005 06 0005PI5 01 20 01 20PI6 5 005 5 005



15 2 25 3 35 404040605

06

Time (s)

Volta

ge D

Cbu

s (kV

)


(a)

minus010

0102

Pow

er (k

W)

and

(kVA

R)

15 2 25 3 35 4

Time (s)

Pg bes offPg bes on

Qg bes offQg bes on

(b)



7 Conclusion


15 2 25 3 35 4minus50

0

50

Time (s)Po

wer

(kW

)

Pbes

(a)

15 2 25 3 35 4

Time (s)

68

69

SOC

()

SOC

(b)

15 2 25 3 35 4

Time (s)

minus15minus050515

Pulse

s (p

u)

S1S2

(c)




0 50 100 150 200

Number of runs

0

005

01

OF

(vol

tage

-mod

e)

0

05

1

OF

(cur

rent

-mod

e)

05

1

15

2

1

2

3

minus05

0

05

1

minus05

0

05

1

1

15

2

1

15

2

0 50 100 150 2000

05

1

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200


Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0

05

1

X 125Y 02026

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

(j)

(h)

kpdc1

kpd3

kidc1

kid3

kpb7

kpb7

kib7

kib7


15 2 25 3 35 4035

045

055

065

Time (s)

Volta

ge (k

V)


(a)

15 2 25 3 35 4

Time (s)

035

045

055

065

Volta

ge (k

V)


(b)







Acknowledgments


References










































Advances in

FuzzySystems


Volume 2014












Journal of

Journal of





Advances in

Multimedia


Biomedical Imaging



Advances in


RoboticsJournal of










Advances in





AC load

DC

DC

DC

DC

DC

ACBES conv

G-VSC

DC-busPV convPV gen

BES

PCC





transformer

PBES

PPVLf0

PG

PL


Ieq

ReqV

I

(a)

Ieqarray

ReqarrayVpv

Ipv

(b)




SOC = 100(1 minusint 119868bat119889119905

119876bat)

(3)




(4)









119875 =119881pcc119881dc

119883119904

119898 sin (120575)

119876 =119881pcc

119883119904

[119881pcc minus 119898119881dc cos (120575)]

(5)






119875 =3

2V119906119889119894119889

119876 = minus3

2V119906119889119894119902

(6)


119894119889ref = (1198961199011198893 + 11989611989411988931

119904) (119881dc minus 119881dcref)

119894119902ref = (1198961199011199024 + 11989611989411990241

119904) (119876 minus 119876ref)

(7)



1198711198910

119889119894119889

119889119905= 1205961198711198910119894119902 + 05119881dc119898119889 minus V119906119889

1198711198910

119889119894119902

119889119905= minus1205961198711198910119894119889 + 05119881dc119898119902 minus V119906119902

(8)



G1G3G5

G4G6G2

VdcDC-bus

ta

tb

tc

Lf0

Idc

ua

ub

uc

PCC(Vpcc )

ita

itb

itc

P Q

(a)

120596

Carrier

Sin

+

Vdc ref

Q ref

PI1

PI2

Limitter

LimitterQm

Phase shift(120∘)

PWM

Vdc120575 G1

G3

G5

G4

G6

G2

minus

+

minus

u abcref-

(b)


Outercontrol loop


+

minusVdc

Q

Vdcref

it abc

120579

abc

dq0

PI4

PI5

PI6

PI3idref

id

iq

iqref

Qref

+

minus +

minus

120596Lf0

120596Lf0

ed

eq uq

ud

md

mq

++

++

+

+

minus minus

udref

uqref

05Vdc

05Vdcabc

abc

dq0

dq0

120579

ud

uq

uq

Carrier

PWM

PLL

G1

G3

G5

G4

G6

G2

undashabc

ndash u abcrefndash



V119906119889ref = V119906119889 + 119906119889 minus 1205961198711198910119894119902

V119906119902ref = V119906119902 + 119906119902 + 1205961198711198910119894119889(9)





VbatIbat


+

Rint

Ebat

SOC

Reset


Ibat

minus

S1

Vdc

L2

S2Limitter

BES model

(a)

Com

S2

S1

Input sig

Vdc

SOC and Vdccontrol

SOC

Ibat ref

Ibat

PI7 PI8+

Vdcref

Vdc

+

Sw control logic

minus minus

(b)







Δ119864 = int119879119904

Δ119875119889119905 =1

2119862dc (119881

2

dc1 minus 1198812

dc0) (10)



119868batref = (1198961199011198877 + 11989611989411988771

119904) (119881dcref minus 119881dc) (11)




MeasureSOC Vdc

SOCL le SOC le SOCH


Boost(discharging)

Halt(no operation)

Halt(no operation)

Buck(charging)

No

Yes

Yes

No

Yes

No

No

Yes

SOC gt SOCH

Vdc gt VdcH

SOC lt SOCL

Vdc lt VdcL






119882ISE = 1198821ISE1 +1198822ISE2 (12)


OF (xdc) = int1198791

1198790

1198821(119881dc minus 119881dcref)2119889119905

+ int

119879119865

1198791

1198822(119881dc minus 119881dcref)2119889119905

(13)


































0 10 20 30 400

2

4

6

8

10

Voltage (V)

Curr

ent (

A)

0

50

100

150

200

250

Pow

er (W

)G = 700Wm2

G = 800Wm2

G = 900Wm2

G = 1000Wm2

G = 1100Wm2

Pmpp

T = 65∘CT = 45∘C

T = 25∘CT = 5∘C

0 10 20 30 400

2

4

6

8

10

Voltage (V)

Curr

ent (

A)

(a)

0 5 10 15 20 25 30 35 400

1

2

3

4

5

6

7

8

9

10

Voltage (V)

Curr

ent (

A)

0 5 10 15 20 25 30 35 400

1

2

3

4

5

6

7

8

9

10

Voltage (V)

Curr

ent (

A)









(b)






100 101 102 103

8

9

10

11

12

13


rmin

al v

olta

ge (V

)



(a)

1 2 4 6 8 10 20 40 60 2 4 6 8 10 20

Discharge time

40

45

50

55

60

65

(V)For 6Vbattery

(V)

batteryFor 12V

80

90

100

110

120

130

Term

inal

vol

tage

3

2

106

0402 01

005

NP AT 25∘C (77 )

(min) Hours

∘F

CACA

CACA

CACA CA CA

(b)



















Inductor 10mH 012mH 04mH 1198711 1198712 1198711198910






aSOC119867 SOC119871


b119881dc119867 119881dc119871










15 2 25 3 35 4

0102

Time (s)

Pow

er (k

W)

Ppv

(a)

15 2 25 3 35 4

Time (s)

5

10

Volta

gePC

C (k

V)

Vpcc rms

(b)

15 2 25 3 35 4

Time (s)

040506

20 sag

Volta

ge D

Cbu

s (kV

)


(c)

15 2 25 3 35 4

Time (s)

minus0101

Pow

er (k

W)

and

(kVA

R)

Pg bes offPg bes on

Qg bes offQg bes on

(d)





15 2 25 3 35 4minus50

0

50

Time (s)

Pow

er (k

W)

DischargingCharging

Pbes

(a)

15 2 25 3 35 4

Time (s)

60

64

68

SOC

()

SOC


(b)

15 2 25 3 35 4

Time (s)

minus15minus050515

Pulse

s (p

u)

S1

S2

Buck modeBoost mode

(c)









PI3 2 0001 1957 00002511PI4 06 0005 06 0005PI5 01 20 01 20PI6 5 005 5 005



15 2 25 3 35 404040605

06

Time (s)

Volta

ge D

Cbu

s (kV

)


(a)

minus010

0102

Pow

er (k

W)

and

(kVA

R)

15 2 25 3 35 4

Time (s)

Pg bes offPg bes on

Qg bes offQg bes on

(b)



7 Conclusion


15 2 25 3 35 4minus50

0

50

Time (s)Po

wer

(kW

)

Pbes

(a)

15 2 25 3 35 4

Time (s)

68

69

SOC

()

SOC

(b)

15 2 25 3 35 4

Time (s)

minus15minus050515

Pulse

s (p

u)

S1S2

(c)




0 50 100 150 200

Number of runs

0

005

01

OF

(vol

tage

-mod

e)

0

05

1

OF

(cur

rent

-mod

e)

05

1

15

2

1

2

3

minus05

0

05

1

minus05

0

05

1

1

15

2

1

15

2

0 50 100 150 2000

05

1

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200


Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0

05

1

X 125Y 02026

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

(j)

(h)

kpdc1

kpd3

kidc1

kid3

kpb7

kpb7

kib7

kib7


15 2 25 3 35 4035

045

055

065

Time (s)

Volta

ge (k

V)


(a)

15 2 25 3 35 4

Time (s)

035

045

055

065

Volta

ge (k

V)


(b)







Acknowledgments


References










































Advances in

FuzzySystems


Volume 2014












Journal of

Journal of





Advances in

Multimedia


Biomedical Imaging



Advances in


RoboticsJournal of










Advances in






119875 =119881pcc119881dc

119883119904

119898 sin (120575)

119876 =119881pcc

119883119904

[119881pcc minus 119898119881dc cos (120575)]

(5)






119875 =3

2V119906119889119894119889

119876 = minus3

2V119906119889119894119902

(6)


119894119889ref = (1198961199011198893 + 11989611989411988931

119904) (119881dc minus 119881dcref)

119894119902ref = (1198961199011199024 + 11989611989411990241

119904) (119876 minus 119876ref)

(7)



1198711198910

119889119894119889

119889119905= 1205961198711198910119894119902 + 05119881dc119898119889 minus V119906119889

1198711198910

119889119894119902

119889119905= minus1205961198711198910119894119889 + 05119881dc119898119902 minus V119906119902

(8)



G1G3G5

G4G6G2

VdcDC-bus

ta

tb

tc

Lf0

Idc

ua

ub

uc

PCC(Vpcc )

ita

itb

itc

P Q

(a)

120596

Carrier

Sin

+

Vdc ref

Q ref

PI1

PI2

Limitter

LimitterQm

Phase shift(120∘)

PWM

Vdc120575 G1

G3

G5

G4

G6

G2

minus

+

minus

u abcref-

(b)


Outercontrol loop


+

minusVdc

Q

Vdcref

it abc

120579

abc

dq0

PI4

PI5

PI6

PI3idref

id

iq

iqref

Qref

+

minus +

minus

120596Lf0

120596Lf0

ed

eq uq

ud

md

mq

++

++

+

+

minus minus

udref

uqref

05Vdc

05Vdcabc

abc

dq0

dq0

120579

ud

uq

uq

Carrier

PWM

PLL

G1

G3

G5

G4

G6

G2

undashabc

ndash u abcrefndash



V119906119889ref = V119906119889 + 119906119889 minus 1205961198711198910119894119902

V119906119902ref = V119906119902 + 119906119902 + 1205961198711198910119894119889(9)





VbatIbat


+

Rint

Ebat

SOC

Reset


Ibat

minus

S1

Vdc

L2

S2Limitter

BES model

(a)

Com

S2

S1

Input sig

Vdc

SOC and Vdccontrol

SOC

Ibat ref

Ibat

PI7 PI8+

Vdcref

Vdc

+

Sw control logic

minus minus

(b)







Δ119864 = int119879119904

Δ119875119889119905 =1

2119862dc (119881

2

dc1 minus 1198812

dc0) (10)



119868batref = (1198961199011198877 + 11989611989411988771

119904) (119881dcref minus 119881dc) (11)




MeasureSOC Vdc

SOCL le SOC le SOCH


Boost(discharging)

Halt(no operation)

Halt(no operation)

Buck(charging)

No

Yes

Yes

No

Yes

No

No

Yes

SOC gt SOCH

Vdc gt VdcH

SOC lt SOCL

Vdc lt VdcL






119882ISE = 1198821ISE1 +1198822ISE2 (12)


OF (xdc) = int1198791

1198790

1198821(119881dc minus 119881dcref)2119889119905

+ int

119879119865

1198791

1198822(119881dc minus 119881dcref)2119889119905

(13)


































0 10 20 30 400

2

4

6

8

10

Voltage (V)

Curr

ent (

A)

0

50

100

150

200

250

Pow

er (W

)G = 700Wm2

G = 800Wm2

G = 900Wm2

G = 1000Wm2

G = 1100Wm2

Pmpp

T = 65∘CT = 45∘C

T = 25∘CT = 5∘C

0 10 20 30 400

2

4

6

8

10

Voltage (V)

Curr

ent (

A)

(a)

0 5 10 15 20 25 30 35 400

1

2

3

4

5

6

7

8

9

10

Voltage (V)

Curr

ent (

A)

0 5 10 15 20 25 30 35 400

1

2

3

4

5

6

7

8

9

10

Voltage (V)

Curr

ent (

A)









(b)






100 101 102 103

8

9

10

11

12

13


rmin

al v

olta

ge (V

)



(a)

1 2 4 6 8 10 20 40 60 2 4 6 8 10 20

Discharge time

40

45

50

55

60

65

(V)For 6Vbattery

(V)

batteryFor 12V

80

90

100

110

120

130

Term

inal

vol

tage

3

2

106

0402 01

005

NP AT 25∘C (77 )

(min) Hours

∘F

CACA

CACA

CACA CA CA

(b)



















Inductor 10mH 012mH 04mH 1198711 1198712 1198711198910






aSOC119867 SOC119871


b119881dc119867 119881dc119871










15 2 25 3 35 4

0102

Time (s)

Pow

er (k

W)

Ppv

(a)

15 2 25 3 35 4

Time (s)

5

10

Volta

gePC

C (k

V)

Vpcc rms

(b)

15 2 25 3 35 4

Time (s)

040506

20 sag

Volta

ge D

Cbu

s (kV

)


(c)

15 2 25 3 35 4

Time (s)

minus0101

Pow

er (k

W)

and

(kVA

R)

Pg bes offPg bes on

Qg bes offQg bes on

(d)





15 2 25 3 35 4minus50

0

50

Time (s)

Pow

er (k

W)

DischargingCharging

Pbes

(a)

15 2 25 3 35 4

Time (s)

60

64

68

SOC

()

SOC


(b)

15 2 25 3 35 4

Time (s)

minus15minus050515

Pulse

s (p

u)

S1

S2

Buck modeBoost mode

(c)









PI3 2 0001 1957 00002511PI4 06 0005 06 0005PI5 01 20 01 20PI6 5 005 5 005



15 2 25 3 35 404040605

06

Time (s)

Volta

ge D

Cbu

s (kV

)


(a)

minus010

0102

Pow

er (k

W)

and

(kVA

R)

15 2 25 3 35 4

Time (s)

Pg bes offPg bes on

Qg bes offQg bes on

(b)



7 Conclusion


15 2 25 3 35 4minus50

0

50

Time (s)Po

wer

(kW

)

Pbes

(a)

15 2 25 3 35 4

Time (s)

68

69

SOC

()

SOC

(b)

15 2 25 3 35 4

Time (s)

minus15minus050515

Pulse

s (p

u)

S1S2

(c)




0 50 100 150 200

Number of runs

0

005

01

OF

(vol

tage

-mod

e)

0

05

1

OF

(cur

rent

-mod

e)

05

1

15

2

1

2

3

minus05

0

05

1

minus05

0

05

1

1

15

2

1

15

2

0 50 100 150 2000

05

1

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200


Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0

05

1

X 125Y 02026

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

(j)

(h)

kpdc1

kpd3

kidc1

kid3

kpb7

kpb7

kib7

kib7


15 2 25 3 35 4035

045

055

065

Time (s)

Volta

ge (k

V)


(a)

15 2 25 3 35 4

Time (s)

035

045

055

065

Volta

ge (k

V)


(b)







Acknowledgments


References










































Advances in

FuzzySystems


Volume 2014












Journal of

Journal of





Advances in

Multimedia


Biomedical Imaging



Advances in


RoboticsJournal of










Advances in




G1G3G5

G4G6G2

VdcDC-bus

ta

tb

tc

Lf0

Idc

ua

ub

uc

PCC(Vpcc )

ita

itb

itc

P Q

(a)

120596

Carrier

Sin

+

Vdc ref

Q ref

PI1

PI2

Limitter

LimitterQm

Phase shift(120∘)

PWM

Vdc120575 G1

G3

G5

G4

G6

G2

minus

+

minus

u abcref-

(b)


Outercontrol loop


+

minusVdc

Q

Vdcref

it abc

120579

abc

dq0

PI4

PI5

PI6

PI3idref

id

iq

iqref

Qref

+

minus +

minus

120596Lf0

120596Lf0

ed

eq uq

ud

md

mq

++

++

+

+

minus minus

udref

uqref

05Vdc

05Vdcabc

abc

dq0

dq0

120579

ud

uq

uq

Carrier

PWM

PLL

G1

G3

G5

G4

G6

G2

undashabc

ndash u abcrefndash



V119906119889ref = V119906119889 + 119906119889 minus 1205961198711198910119894119902

V119906119902ref = V119906119902 + 119906119902 + 1205961198711198910119894119889(9)





VbatIbat


+

Rint

Ebat

SOC

Reset


Ibat

minus

S1

Vdc

L2

S2Limitter

BES model

(a)

Com

S2

S1

Input sig

Vdc

SOC and Vdccontrol

SOC

Ibat ref

Ibat

PI7 PI8+

Vdcref

Vdc

+

Sw control logic

minus minus

(b)







Δ119864 = int119879119904

Δ119875119889119905 =1

2119862dc (119881

2

dc1 minus 1198812

dc0) (10)



119868batref = (1198961199011198877 + 11989611989411988771

119904) (119881dcref minus 119881dc) (11)




MeasureSOC Vdc

SOCL le SOC le SOCH


Boost(discharging)

Halt(no operation)

Halt(no operation)

Buck(charging)

No

Yes

Yes

No

Yes

No

No

Yes

SOC gt SOCH

Vdc gt VdcH

SOC lt SOCL

Vdc lt VdcL






119882ISE = 1198821ISE1 +1198822ISE2 (12)


OF (xdc) = int1198791

1198790

1198821(119881dc minus 119881dcref)2119889119905

+ int

119879119865

1198791

1198822(119881dc minus 119881dcref)2119889119905

(13)


































0 10 20 30 400

2

4

6

8

10

Voltage (V)

Curr

ent (

A)

0

50

100

150

200

250

Pow

er (W

)G = 700Wm2

G = 800Wm2

G = 900Wm2

G = 1000Wm2

G = 1100Wm2

Pmpp

T = 65∘CT = 45∘C

T = 25∘CT = 5∘C

0 10 20 30 400

2

4

6

8

10

Voltage (V)

Curr

ent (

A)

(a)

0 5 10 15 20 25 30 35 400

1

2

3

4

5

6

7

8

9

10

Voltage (V)

Curr

ent (

A)

0 5 10 15 20 25 30 35 400

1

2

3

4

5

6

7

8

9

10

Voltage (V)

Curr

ent (

A)









(b)






100 101 102 103

8

9

10

11

12

13


rmin

al v

olta

ge (V

)



(a)

1 2 4 6 8 10 20 40 60 2 4 6 8 10 20

Discharge time

40

45

50

55

60

65

(V)For 6Vbattery

(V)

batteryFor 12V

80

90

100

110

120

130

Term

inal

vol

tage

3

2

106

0402 01

005

NP AT 25∘C (77 )

(min) Hours

∘F

CACA

CACA

CACA CA CA

(b)



















Inductor 10mH 012mH 04mH 1198711 1198712 1198711198910






aSOC119867 SOC119871


b119881dc119867 119881dc119871










15 2 25 3 35 4

0102

Time (s)

Pow

er (k

W)

Ppv

(a)

15 2 25 3 35 4

Time (s)

5

10

Volta

gePC

C (k

V)

Vpcc rms

(b)

15 2 25 3 35 4

Time (s)

040506

20 sag

Volta

ge D

Cbu

s (kV

)


(c)

15 2 25 3 35 4

Time (s)

minus0101

Pow

er (k

W)

and

(kVA

R)

Pg bes offPg bes on

Qg bes offQg bes on

(d)





15 2 25 3 35 4minus50

0

50

Time (s)

Pow

er (k

W)

DischargingCharging

Pbes

(a)

15 2 25 3 35 4

Time (s)

60

64

68

SOC

()

SOC


(b)

15 2 25 3 35 4

Time (s)

minus15minus050515

Pulse

s (p

u)

S1

S2

Buck modeBoost mode

(c)









PI3 2 0001 1957 00002511PI4 06 0005 06 0005PI5 01 20 01 20PI6 5 005 5 005



15 2 25 3 35 404040605

06

Time (s)

Volta

ge D

Cbu

s (kV

)


(a)

minus010

0102

Pow

er (k

W)

and

(kVA

R)

15 2 25 3 35 4

Time (s)

Pg bes offPg bes on

Qg bes offQg bes on

(b)



7 Conclusion


15 2 25 3 35 4minus50

0

50

Time (s)Po

wer

(kW

)

Pbes

(a)

15 2 25 3 35 4

Time (s)

68

69

SOC

()

SOC

(b)

15 2 25 3 35 4

Time (s)

minus15minus050515

Pulse

s (p

u)

S1S2

(c)




0 50 100 150 200

Number of runs

0

005

01

OF

(vol

tage

-mod

e)

0

05

1

OF

(cur

rent

-mod

e)

05

1

15

2

1

2

3

minus05

0

05

1

minus05

0

05

1

1

15

2

1

15

2

0 50 100 150 2000

05

1

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200


Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0

05

1

X 125Y 02026

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

(j)

(h)

kpdc1

kpd3

kidc1

kid3

kpb7

kpb7

kib7

kib7


15 2 25 3 35 4035

045

055

065

Time (s)

Volta

ge (k

V)


(a)

15 2 25 3 35 4

Time (s)

035

045

055

065

Volta

ge (k

V)


(b)







Acknowledgments


References










































Advances in

FuzzySystems


Volume 2014












Journal of

Journal of





Advances in

Multimedia


Biomedical Imaging



Advances in


RoboticsJournal of










Advances in




VbatIbat


+

Rint

Ebat

SOC

Reset


Ibat

minus

S1

Vdc

L2

S2Limitter

BES model

(a)

Com

S2

S1

Input sig

Vdc

SOC and Vdccontrol

SOC

Ibat ref

Ibat

PI7 PI8+

Vdcref

Vdc

+

Sw control logic

minus minus

(b)







Δ119864 = int119879119904

Δ119875119889119905 =1

2119862dc (119881

2

dc1 minus 1198812

dc0) (10)



119868batref = (1198961199011198877 + 11989611989411988771

119904) (119881dcref minus 119881dc) (11)




MeasureSOC Vdc

SOCL le SOC le SOCH


Boost(discharging)

Halt(no operation)

Halt(no operation)

Buck(charging)

No

Yes

Yes

No

Yes

No

No

Yes

SOC gt SOCH

Vdc gt VdcH

SOC lt SOCL

Vdc lt VdcL






119882ISE = 1198821ISE1 +1198822ISE2 (12)


OF (xdc) = int1198791

1198790

1198821(119881dc minus 119881dcref)2119889119905

+ int

119879119865

1198791

1198822(119881dc minus 119881dcref)2119889119905

(13)


































0 10 20 30 400

2

4

6

8

10

Voltage (V)

Curr

ent (

A)

0

50

100

150

200

250

Pow

er (W

)G = 700Wm2

G = 800Wm2

G = 900Wm2

G = 1000Wm2

G = 1100Wm2

Pmpp

T = 65∘CT = 45∘C

T = 25∘CT = 5∘C

0 10 20 30 400

2

4

6

8

10

Voltage (V)

Curr

ent (

A)

(a)

0 5 10 15 20 25 30 35 400

1

2

3

4

5

6

7

8

9

10

Voltage (V)

Curr

ent (

A)

0 5 10 15 20 25 30 35 400

1

2

3

4

5

6

7

8

9

10

Voltage (V)

Curr

ent (

A)









(b)






100 101 102 103

8

9

10

11

12

13


rmin

al v

olta

ge (V

)



(a)

1 2 4 6 8 10 20 40 60 2 4 6 8 10 20

Discharge time

40

45

50

55

60

65

(V)For 6Vbattery

(V)

batteryFor 12V

80

90

100

110

120

130

Term

inal

vol

tage

3

2

106

0402 01

005

NP AT 25∘C (77 )

(min) Hours

∘F

CACA

CACA

CACA CA CA

(b)



















Inductor 10mH 012mH 04mH 1198711 1198712 1198711198910






aSOC119867 SOC119871


b119881dc119867 119881dc119871










15 2 25 3 35 4

0102

Time (s)

Pow

er (k

W)

Ppv

(a)

15 2 25 3 35 4

Time (s)

5

10

Volta

gePC

C (k

V)

Vpcc rms

(b)

15 2 25 3 35 4

Time (s)

040506

20 sag

Volta

ge D

Cbu

s (kV

)


(c)

15 2 25 3 35 4

Time (s)

minus0101

Pow

er (k

W)

and

(kVA

R)

Pg bes offPg bes on

Qg bes offQg bes on

(d)





15 2 25 3 35 4minus50

0

50

Time (s)

Pow

er (k

W)

DischargingCharging

Pbes

(a)

15 2 25 3 35 4

Time (s)

60

64

68

SOC

()

SOC


(b)

15 2 25 3 35 4

Time (s)

minus15minus050515

Pulse

s (p

u)

S1

S2

Buck modeBoost mode

(c)









PI3 2 0001 1957 00002511PI4 06 0005 06 0005PI5 01 20 01 20PI6 5 005 5 005



15 2 25 3 35 404040605

06

Time (s)

Volta

ge D

Cbu

s (kV

)


(a)

minus010

0102

Pow

er (k

W)

and

(kVA

R)

15 2 25 3 35 4

Time (s)

Pg bes offPg bes on

Qg bes offQg bes on

(b)



7 Conclusion


15 2 25 3 35 4minus50

0

50

Time (s)Po

wer

(kW

)

Pbes

(a)

15 2 25 3 35 4

Time (s)

68

69

SOC

()

SOC

(b)

15 2 25 3 35 4

Time (s)

minus15minus050515

Pulse

s (p

u)

S1S2

(c)




0 50 100 150 200

Number of runs

0

005

01

OF

(vol

tage

-mod

e)

0

05

1

OF

(cur

rent

-mod

e)

05

1

15

2

1

2

3

minus05

0

05

1

minus05

0

05

1

1

15

2

1

15

2

0 50 100 150 2000

05

1

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200


Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0

05

1

X 125Y 02026

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

(j)

(h)

kpdc1

kpd3

kidc1

kid3

kpb7

kpb7

kib7

kib7


15 2 25 3 35 4035

045

055

065

Time (s)

Volta

ge (k

V)


(a)

15 2 25 3 35 4

Time (s)

035

045

055

065

Volta

ge (k

V)


(b)







Acknowledgments


References










































Advances in

FuzzySystems


Volume 2014












Journal of

Journal of





Advances in

Multimedia


Biomedical Imaging



Advances in


RoboticsJournal of










Advances in




MeasureSOC Vdc

SOCL le SOC le SOCH


Boost(discharging)

Halt(no operation)

Halt(no operation)

Buck(charging)

No

Yes

Yes

No

Yes

No

No

Yes

SOC gt SOCH

Vdc gt VdcH

SOC lt SOCL

Vdc lt VdcL






119882ISE = 1198821ISE1 +1198822ISE2 (12)


OF (xdc) = int1198791

1198790

1198821(119881dc minus 119881dcref)2119889119905

+ int

119879119865

1198791

1198822(119881dc minus 119881dcref)2119889119905

(13)


































0 10 20 30 400

2

4

6

8

10

Voltage (V)

Curr

ent (

A)

0

50

100

150

200

250

Pow

er (W

)G = 700Wm2

G = 800Wm2

G = 900Wm2

G = 1000Wm2

G = 1100Wm2

Pmpp

T = 65∘CT = 45∘C

T = 25∘CT = 5∘C

0 10 20 30 400

2

4

6

8

10

Voltage (V)

Curr

ent (

A)

(a)

0 5 10 15 20 25 30 35 400

1

2

3

4

5

6

7

8

9

10

Voltage (V)

Curr

ent (

A)

0 5 10 15 20 25 30 35 400

1

2

3

4

5

6

7

8

9

10

Voltage (V)

Curr

ent (

A)









(b)






100 101 102 103

8

9

10

11

12

13


rmin

al v

olta

ge (V

)



(a)

1 2 4 6 8 10 20 40 60 2 4 6 8 10 20

Discharge time

40

45

50

55

60

65

(V)For 6Vbattery

(V)

batteryFor 12V

80

90

100

110

120

130

Term

inal

vol

tage

3

2

106

0402 01

005

NP AT 25∘C (77 )

(min) Hours

∘F

CACA

CACA

CACA CA CA

(b)



















Inductor 10mH 012mH 04mH 1198711 1198712 1198711198910






aSOC119867 SOC119871


b119881dc119867 119881dc119871










15 2 25 3 35 4

0102

Time (s)

Pow

er (k

W)

Ppv

(a)

15 2 25 3 35 4

Time (s)

5

10

Volta

gePC

C (k

V)

Vpcc rms

(b)

15 2 25 3 35 4

Time (s)

040506

20 sag

Volta

ge D

Cbu

s (kV

)


(c)

15 2 25 3 35 4

Time (s)

minus0101

Pow

er (k

W)

and

(kVA

R)

Pg bes offPg bes on

Qg bes offQg bes on

(d)





15 2 25 3 35 4minus50

0

50

Time (s)

Pow

er (k

W)

DischargingCharging

Pbes

(a)

15 2 25 3 35 4

Time (s)

60

64

68

SOC

()

SOC


(b)

15 2 25 3 35 4

Time (s)

minus15minus050515

Pulse

s (p

u)

S1

S2

Buck modeBoost mode

(c)









PI3 2 0001 1957 00002511PI4 06 0005 06 0005PI5 01 20 01 20PI6 5 005 5 005



15 2 25 3 35 404040605

06

Time (s)

Volta

ge D

Cbu

s (kV

)


(a)

minus010

0102

Pow

er (k

W)

and

(kVA

R)

15 2 25 3 35 4

Time (s)

Pg bes offPg bes on

Qg bes offQg bes on

(b)



7 Conclusion


15 2 25 3 35 4minus50

0

50

Time (s)Po

wer

(kW

)

Pbes

(a)

15 2 25 3 35 4

Time (s)

68

69

SOC

()

SOC

(b)

15 2 25 3 35 4

Time (s)

minus15minus050515

Pulse

s (p

u)

S1S2

(c)




0 50 100 150 200

Number of runs

0

005

01

OF

(vol

tage

-mod

e)

0

05

1

OF

(cur

rent

-mod

e)

05

1

15

2

1

2

3

minus05

0

05

1

minus05

0

05

1

1

15

2

1

15

2

0 50 100 150 2000

05

1

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200


Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0

05

1

X 125Y 02026

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

(j)

(h)

kpdc1

kpd3

kidc1

kid3

kpb7

kpb7

kib7

kib7


15 2 25 3 35 4035

045

055

065

Time (s)

Volta

ge (k

V)


(a)

15 2 25 3 35 4

Time (s)

035

045

055

065

Volta

ge (k

V)


(b)







Acknowledgments


References










































Advances in

FuzzySystems


Volume 2014












Journal of

Journal of





Advances in

Multimedia


Biomedical Imaging



Advances in


RoboticsJournal of










Advances in



































0 10 20 30 400

2

4

6

8

10

Voltage (V)

Curr

ent (

A)

0

50

100

150

200

250

Pow

er (W

)G = 700Wm2

G = 800Wm2

G = 900Wm2

G = 1000Wm2

G = 1100Wm2

Pmpp

T = 65∘CT = 45∘C

T = 25∘CT = 5∘C

0 10 20 30 400

2

4

6

8

10

Voltage (V)

Curr

ent (

A)

(a)

0 5 10 15 20 25 30 35 400

1

2

3

4

5

6

7

8

9

10

Voltage (V)

Curr

ent (

A)

0 5 10 15 20 25 30 35 400

1

2

3

4

5

6

7

8

9

10

Voltage (V)

Curr

ent (

A)









(b)






100 101 102 103

8

9

10

11

12

13


rmin

al v

olta

ge (V

)



(a)

1 2 4 6 8 10 20 40 60 2 4 6 8 10 20

Discharge time

40

45

50

55

60

65

(V)For 6Vbattery

(V)

batteryFor 12V

80

90

100

110

120

130

Term

inal

vol

tage

3

2

106

0402 01

005

NP AT 25∘C (77 )

(min) Hours

∘F

CACA

CACA

CACA CA CA

(b)



















Inductor 10mH 012mH 04mH 1198711 1198712 1198711198910






aSOC119867 SOC119871


b119881dc119867 119881dc119871










15 2 25 3 35 4

0102

Time (s)

Pow

er (k

W)

Ppv

(a)

15 2 25 3 35 4

Time (s)

5

10

Volta

gePC

C (k

V)

Vpcc rms

(b)

15 2 25 3 35 4

Time (s)

040506

20 sag

Volta

ge D

Cbu

s (kV

)


(c)

15 2 25 3 35 4

Time (s)

minus0101

Pow

er (k

W)

and

(kVA

R)

Pg bes offPg bes on

Qg bes offQg bes on

(d)





15 2 25 3 35 4minus50

0

50

Time (s)

Pow

er (k

W)

DischargingCharging

Pbes

(a)

15 2 25 3 35 4

Time (s)

60

64

68

SOC

()

SOC


(b)

15 2 25 3 35 4

Time (s)

minus15minus050515

Pulse

s (p

u)

S1

S2

Buck modeBoost mode

(c)









PI3 2 0001 1957 00002511PI4 06 0005 06 0005PI5 01 20 01 20PI6 5 005 5 005



15 2 25 3 35 404040605

06

Time (s)

Volta

ge D

Cbu

s (kV

)


(a)

minus010

0102

Pow

er (k

W)

and

(kVA

R)

15 2 25 3 35 4

Time (s)

Pg bes offPg bes on

Qg bes offQg bes on

(b)



7 Conclusion


15 2 25 3 35 4minus50

0

50

Time (s)Po

wer

(kW

)

Pbes

(a)

15 2 25 3 35 4

Time (s)

68

69

SOC

()

SOC

(b)

15 2 25 3 35 4

Time (s)

minus15minus050515

Pulse

s (p

u)

S1S2

(c)




0 50 100 150 200

Number of runs

0

005

01

OF

(vol

tage

-mod

e)

0

05

1

OF

(cur

rent

-mod

e)

05

1

15

2

1

2

3

minus05

0

05

1

minus05

0

05

1

1

15

2

1

15

2

0 50 100 150 2000

05

1

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200


Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0

05

1

X 125Y 02026

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

(j)

(h)

kpdc1

kpd3

kidc1

kid3

kpb7

kpb7

kib7

kib7


15 2 25 3 35 4035

045

055

065

Time (s)

Volta

ge (k

V)


(a)

15 2 25 3 35 4

Time (s)

035

045

055

065

Volta

ge (k

V)


(b)







Acknowledgments


References










































Advances in

FuzzySystems


Volume 2014












Journal of

Journal of





Advances in

Multimedia


Biomedical Imaging



Advances in


RoboticsJournal of










Advances in




0 10 20 30 400

2

4

6

8

10

Voltage (V)

Curr

ent (

A)

0

50

100

150

200

250

Pow

er (W

)G = 700Wm2

G = 800Wm2

G = 900Wm2

G = 1000Wm2

G = 1100Wm2

Pmpp

T = 65∘CT = 45∘C

T = 25∘CT = 5∘C

0 10 20 30 400

2

4

6

8

10

Voltage (V)

Curr

ent (

A)

(a)

0 5 10 15 20 25 30 35 400

1

2

3

4

5

6

7

8

9

10

Voltage (V)

Curr

ent (

A)

0 5 10 15 20 25 30 35 400

1

2

3

4

5

6

7

8

9

10

Voltage (V)

Curr

ent (

A)









(b)






100 101 102 103

8

9

10

11

12

13


rmin

al v

olta

ge (V

)



(a)

1 2 4 6 8 10 20 40 60 2 4 6 8 10 20

Discharge time

40

45

50

55

60

65

(V)For 6Vbattery

(V)

batteryFor 12V

80

90

100

110

120

130

Term

inal

vol

tage

3

2

106

0402 01

005

NP AT 25∘C (77 )

(min) Hours

∘F

CACA

CACA

CACA CA CA

(b)



















Inductor 10mH 012mH 04mH 1198711 1198712 1198711198910






aSOC119867 SOC119871


b119881dc119867 119881dc119871










15 2 25 3 35 4

0102

Time (s)

Pow

er (k

W)

Ppv

(a)

15 2 25 3 35 4

Time (s)

5

10

Volta

gePC

C (k

V)

Vpcc rms

(b)

15 2 25 3 35 4

Time (s)

040506

20 sag

Volta

ge D

Cbu

s (kV

)


(c)

15 2 25 3 35 4

Time (s)

minus0101

Pow

er (k

W)

and

(kVA

R)

Pg bes offPg bes on

Qg bes offQg bes on

(d)





15 2 25 3 35 4minus50

0

50

Time (s)

Pow

er (k

W)

DischargingCharging

Pbes

(a)

15 2 25 3 35 4

Time (s)

60

64

68

SOC

()

SOC


(b)

15 2 25 3 35 4

Time (s)

minus15minus050515

Pulse

s (p

u)

S1

S2

Buck modeBoost mode

(c)









PI3 2 0001 1957 00002511PI4 06 0005 06 0005PI5 01 20 01 20PI6 5 005 5 005



15 2 25 3 35 404040605

06

Time (s)

Volta

ge D

Cbu

s (kV

)


(a)

minus010

0102

Pow

er (k

W)

and

(kVA

R)

15 2 25 3 35 4

Time (s)

Pg bes offPg bes on

Qg bes offQg bes on

(b)



7 Conclusion


15 2 25 3 35 4minus50

0

50

Time (s)Po

wer

(kW

)

Pbes

(a)

15 2 25 3 35 4

Time (s)

68

69

SOC

()

SOC

(b)

15 2 25 3 35 4

Time (s)

minus15minus050515

Pulse

s (p

u)

S1S2

(c)




0 50 100 150 200

Number of runs

0

005

01

OF

(vol

tage

-mod

e)

0

05

1

OF

(cur

rent

-mod

e)

05

1

15

2

1

2

3

minus05

0

05

1

minus05

0

05

1

1

15

2

1

15

2

0 50 100 150 2000

05

1

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200


Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0

05

1

X 125Y 02026

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

(j)

(h)

kpdc1

kpd3

kidc1

kid3

kpb7

kpb7

kib7

kib7


15 2 25 3 35 4035

045

055

065

Time (s)

Volta

ge (k

V)


(a)

15 2 25 3 35 4

Time (s)

035

045

055

065

Volta

ge (k

V)


(b)







Acknowledgments


References










































Advances in

FuzzySystems


Volume 2014












Journal of

Journal of





Advances in

Multimedia


Biomedical Imaging



Advances in


RoboticsJournal of










Advances in




100 101 102 103

8

9

10

11

12

13


rmin

al v

olta

ge (V

)



(a)

1 2 4 6 8 10 20 40 60 2 4 6 8 10 20

Discharge time

40

45

50

55

60

65

(V)For 6Vbattery

(V)

batteryFor 12V

80

90

100

110

120

130

Term

inal

vol

tage

3

2

106

0402 01

005

NP AT 25∘C (77 )

(min) Hours

∘F

CACA

CACA

CACA CA CA

(b)



















Inductor 10mH 012mH 04mH 1198711 1198712 1198711198910






aSOC119867 SOC119871


b119881dc119867 119881dc119871










15 2 25 3 35 4

0102

Time (s)

Pow

er (k

W)

Ppv

(a)

15 2 25 3 35 4

Time (s)

5

10

Volta

gePC

C (k

V)

Vpcc rms

(b)

15 2 25 3 35 4

Time (s)

040506

20 sag

Volta

ge D

Cbu

s (kV

)


(c)

15 2 25 3 35 4

Time (s)

minus0101

Pow

er (k

W)

and

(kVA

R)

Pg bes offPg bes on

Qg bes offQg bes on

(d)





15 2 25 3 35 4minus50

0

50

Time (s)

Pow

er (k

W)

DischargingCharging

Pbes

(a)

15 2 25 3 35 4

Time (s)

60

64

68

SOC

()

SOC


(b)

15 2 25 3 35 4

Time (s)

minus15minus050515

Pulse

s (p

u)

S1

S2

Buck modeBoost mode

(c)









PI3 2 0001 1957 00002511PI4 06 0005 06 0005PI5 01 20 01 20PI6 5 005 5 005



15 2 25 3 35 404040605

06

Time (s)

Volta

ge D

Cbu

s (kV

)


(a)

minus010

0102

Pow

er (k

W)

and

(kVA

R)

15 2 25 3 35 4

Time (s)

Pg bes offPg bes on

Qg bes offQg bes on

(b)



7 Conclusion


15 2 25 3 35 4minus50

0

50

Time (s)Po

wer

(kW

)

Pbes

(a)

15 2 25 3 35 4

Time (s)

68

69

SOC

()

SOC

(b)

15 2 25 3 35 4

Time (s)

minus15minus050515

Pulse

s (p

u)

S1S2

(c)




0 50 100 150 200

Number of runs

0

005

01

OF

(vol

tage

-mod

e)

0

05

1

OF

(cur

rent

-mod

e)

05

1

15

2

1

2

3

minus05

0

05

1

minus05

0

05

1

1

15

2

1

15

2

0 50 100 150 2000

05

1

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200


Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0

05

1

X 125Y 02026

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

(j)

(h)

kpdc1

kpd3

kidc1

kid3

kpb7

kpb7

kib7

kib7


15 2 25 3 35 4035

045

055

065

Time (s)

Volta

ge (k

V)


(a)

15 2 25 3 35 4

Time (s)

035

045

055

065

Volta

ge (k

V)


(b)







Acknowledgments


References










































Advances in

FuzzySystems


Volume 2014












Journal of

Journal of





Advances in

Multimedia


Biomedical Imaging



Advances in


RoboticsJournal of










Advances in















Inductor 10mH 012mH 04mH 1198711 1198712 1198711198910






aSOC119867 SOC119871


b119881dc119867 119881dc119871










15 2 25 3 35 4

0102

Time (s)

Pow

er (k

W)

Ppv

(a)

15 2 25 3 35 4

Time (s)

5

10

Volta

gePC

C (k

V)

Vpcc rms

(b)

15 2 25 3 35 4

Time (s)

040506

20 sag

Volta

ge D

Cbu

s (kV

)


(c)

15 2 25 3 35 4

Time (s)

minus0101

Pow

er (k

W)

and

(kVA

R)

Pg bes offPg bes on

Qg bes offQg bes on

(d)





15 2 25 3 35 4minus50

0

50

Time (s)

Pow

er (k

W)

DischargingCharging

Pbes

(a)

15 2 25 3 35 4

Time (s)

60

64

68

SOC

()

SOC


(b)

15 2 25 3 35 4

Time (s)

minus15minus050515

Pulse

s (p

u)

S1

S2

Buck modeBoost mode

(c)









PI3 2 0001 1957 00002511PI4 06 0005 06 0005PI5 01 20 01 20PI6 5 005 5 005



15 2 25 3 35 404040605

06

Time (s)

Volta

ge D

Cbu

s (kV

)


(a)

minus010

0102

Pow

er (k

W)

and

(kVA

R)

15 2 25 3 35 4

Time (s)

Pg bes offPg bes on

Qg bes offQg bes on

(b)



7 Conclusion


15 2 25 3 35 4minus50

0

50

Time (s)Po

wer

(kW

)

Pbes

(a)

15 2 25 3 35 4

Time (s)

68

69

SOC

()

SOC

(b)

15 2 25 3 35 4

Time (s)

minus15minus050515

Pulse

s (p

u)

S1S2

(c)




0 50 100 150 200

Number of runs

0

005

01

OF

(vol

tage

-mod

e)

0

05

1

OF

(cur

rent

-mod

e)

05

1

15

2

1

2

3

minus05

0

05

1

minus05

0

05

1

1

15

2

1

15

2

0 50 100 150 2000

05

1

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200


Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0

05

1

X 125Y 02026

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

(j)

(h)

kpdc1

kpd3

kidc1

kid3

kpb7

kpb7

kib7

kib7


15 2 25 3 35 4035

045

055

065

Time (s)

Volta

ge (k

V)


(a)

15 2 25 3 35 4

Time (s)

035

045

055

065

Volta

ge (k

V)


(b)







Acknowledgments


References










































Advances in

FuzzySystems


Volume 2014












Journal of

Journal of





Advances in

Multimedia


Biomedical Imaging



Advances in


RoboticsJournal of










Advances in




15 2 25 3 35 4

0102

Time (s)

Pow

er (k

W)

Ppv

(a)

15 2 25 3 35 4

Time (s)

5

10

Volta

gePC

C (k

V)

Vpcc rms

(b)

15 2 25 3 35 4

Time (s)

040506

20 sag

Volta

ge D

Cbu

s (kV

)


(c)

15 2 25 3 35 4

Time (s)

minus0101

Pow

er (k

W)

and

(kVA

R)

Pg bes offPg bes on

Qg bes offQg bes on

(d)





15 2 25 3 35 4minus50

0

50

Time (s)

Pow

er (k

W)

DischargingCharging

Pbes

(a)

15 2 25 3 35 4

Time (s)

60

64

68

SOC

()

SOC


(b)

15 2 25 3 35 4

Time (s)

minus15minus050515

Pulse

s (p

u)

S1

S2

Buck modeBoost mode

(c)









PI3 2 0001 1957 00002511PI4 06 0005 06 0005PI5 01 20 01 20PI6 5 005 5 005



15 2 25 3 35 404040605

06

Time (s)

Volta

ge D

Cbu

s (kV

)


(a)

minus010

0102

Pow

er (k

W)

and

(kVA

R)

15 2 25 3 35 4

Time (s)

Pg bes offPg bes on

Qg bes offQg bes on

(b)



7 Conclusion


15 2 25 3 35 4minus50

0

50

Time (s)Po

wer

(kW

)

Pbes

(a)

15 2 25 3 35 4

Time (s)

68

69

SOC

()

SOC

(b)

15 2 25 3 35 4

Time (s)

minus15minus050515

Pulse

s (p

u)

S1S2

(c)




0 50 100 150 200

Number of runs

0

005

01

OF

(vol

tage

-mod

e)

0

05

1

OF

(cur

rent

-mod

e)

05

1

15

2

1

2

3

minus05

0

05

1

minus05

0

05

1

1

15

2

1

15

2

0 50 100 150 2000

05

1

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200


Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0

05

1

X 125Y 02026

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

(j)

(h)

kpdc1

kpd3

kidc1

kid3

kpb7

kpb7

kib7

kib7


15 2 25 3 35 4035

045

055

065

Time (s)

Volta

ge (k

V)


(a)

15 2 25 3 35 4

Time (s)

035

045

055

065

Volta

ge (k

V)


(b)







Acknowledgments


References










































Advances in

FuzzySystems


Volume 2014












Journal of

Journal of





Advances in

Multimedia


Biomedical Imaging



Advances in


RoboticsJournal of










Advances in








PI3 2 0001 1957 00002511PI4 06 0005 06 0005PI5 01 20 01 20PI6 5 005 5 005



15 2 25 3 35 404040605

06

Time (s)

Volta

ge D

Cbu

s (kV

)


(a)

minus010

0102

Pow

er (k

W)

and

(kVA

R)

15 2 25 3 35 4

Time (s)

Pg bes offPg bes on

Qg bes offQg bes on

(b)



7 Conclusion


15 2 25 3 35 4minus50

0

50

Time (s)Po

wer

(kW

)

Pbes

(a)

15 2 25 3 35 4

Time (s)

68

69

SOC

()

SOC

(b)

15 2 25 3 35 4

Time (s)

minus15minus050515

Pulse

s (p

u)

S1S2

(c)




0 50 100 150 200

Number of runs

0

005

01

OF

(vol

tage

-mod

e)

0

05

1

OF

(cur

rent

-mod

e)

05

1

15

2

1

2

3

minus05

0

05

1

minus05

0

05

1

1

15

2

1

15

2

0 50 100 150 2000

05

1

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200


Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0

05

1

X 125Y 02026

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

(j)

(h)

kpdc1

kpd3

kidc1

kid3

kpb7

kpb7

kib7

kib7


15 2 25 3 35 4035

045

055

065

Time (s)

Volta

ge (k

V)


(a)

15 2 25 3 35 4

Time (s)

035

045

055

065

Volta

ge (k

V)


(b)







Acknowledgments


References










































Advances in

FuzzySystems


Volume 2014












Journal of

Journal of





Advances in

Multimedia


Biomedical Imaging



Advances in


RoboticsJournal of










Advances in




0 50 100 150 200

Number of runs

0

005

01

OF

(vol

tage

-mod

e)

0

05

1

OF

(cur

rent

-mod

e)

05

1

15

2

1

2

3

minus05

0

05

1

minus05

0

05

1

1

15

2

1

15

2

0 50 100 150 2000

05

1

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200


Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0 50 100 150 200

Number of runs

0

05

1

X 125Y 02026

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

(j)

(h)

kpdc1

kpd3

kidc1

kid3

kpb7

kpb7

kib7

kib7


15 2 25 3 35 4035

045

055

065

Time (s)

Volta

ge (k

V)


(a)

15 2 25 3 35 4

Time (s)

035

045

055

065

Volta

ge (k

V)


(b)







Acknowledgments


References










































Advances in

FuzzySystems


Volume 2014












Journal of

Journal of





Advances in

Multimedia


Biomedical Imaging



Advances in


RoboticsJournal of










Advances in






Acknowledgments


References










































Advances in

FuzzySystems


Volume 2014












Journal of

Journal of





Advances in

Multimedia


Biomedical Imaging



Advances in


RoboticsJournal of










Advances in














Advances in

FuzzySystems


Volume 2014












Journal of

Journal of





Advances in

Multimedia


Biomedical Imaging



Advances in


RoboticsJournal of










Advances in










Advances in

FuzzySystems


Volume 2014












Journal of

Journal of





Advances in

Multimedia


Biomedical Imaging



Advances in


RoboticsJournal of










Advances in



Documents

Research Article An Optimal Control Strategy for DC Bus ...downloads.hindawi.com/journals/tswj/2014/271087.pdf · An Optimal Control Strategy for DC Bus Voltage Regulation in Photovoltaic